Category: Geography Notes PPT

The tsunami definition states that “A series of waves triggered by the movement of a large amount of water in a water body, typically an ocean or a large lake”.

The tsunami definition tells us that these are waves so tsunamis are also known as tidal waves. Tsunamis and tides both create inland water waves, but the inland movement of water in the case of a tsunami can be much greater, giving the appearance of an extremely high and strong tide called a tsunami wave.

In this article on tsunamis, we will learn about the causes and effects of tsunamis, types of tsunamis, and more tsunami information.

What is the Spelling of the Tsunami?

Tsunami is derived from the Japanese word “soo-NAH-mee”. The tsunami meaning in Japanese is “harbour wave”. Since in Japanese words, there is no ‘T’. So when spelt the initial ‘T’ is often silent which fits with the phonological rules of English.

So, the correct spelling of Tsunami is “Tsunami” with ‘T’ a silent letter.

How Tsunami Occurs?

• Tsunamis may be caused by earthquakes, volcanic eruptions, and other underwater explosions such as detonations, landslides, glacier calvings, meteorite impacts, and other man-made disruptions above or below water.

• The movement of a large amount of water or the perturbation of the sea is the primary cause of a tsunami. Earthquakes, landslides, volcanic eruptions, ice calvings, and, more rarely, meteorites and nuclear tests are all accounted for the water displacement. 

• Earthquakes are the major cause of tsunamis that occur worldwide.

• Let us look into a detailed explanation of tsunami causes.

1. The Tsunami Caused By Earthquake

• When the seafloor suddenly deforms and vertically displaces the overlying water, tsunamis may occur.

• Tectonic earthquakes are a type of earthquake that is related to the deformation of the Earth’s crust. When these earthquakes happen under the sea, the water above the deformed region is displaced from its equilibrium state.

• Because of the vertical component of movement involved, a tsunami can be produced when thrust faults associated with convergent or destructive plate boundaries move suddenly, resulting in water displacement.

• Tsunamis have a small wave height offshore and a long wavelength, which is why they go unnoticed at sea, creating just a small swell about 300 mm (12 in) above the normal sea level. 

• When they enter shallow water, they rise in height, a process known as wave shoaling. A tsunami can occur at any tidal state, and coastal areas can be inundated even at low tide.

• Examples of tsunamis caused by earthquakes are the Aleutian Islands earthquake in 1946, the Valdivia earthquake in 1960, the Alaska earthquake in 1964, the Indian Ocean earthquake in 2004, the Tōhoku earthquake in 2011.

2. The Tsunami Caused By Landslides

• Landslides cause displacements mostly along the shallower sections of the coastline, and the extent of large landslides that hit the water is uncertain. 

• Water in enclosed bays and lakes has been shown to be disturbed as a result, but no landslide large enough to cause a transoceanic tsunami has ever occurred in recorded history.

3. The Tsunami Caused By Meteorological Conditions

• The tsunami caused due to Meteorological changes is called a Meteotsunami.

• Rapid changes in barometric pressure, such as those seen when a front passes through, can displace bodies of water enough to cause trains of waves with wavelengths similar to seismic tsunamis, but with lower energies.

• These are basically dynamically similar to seismic tsunamis, with the exception that Meteotsunami lacks the transoceanic scope of substantial seismic tsunamis and that the force that displaces the water is maintained over time, preventing Meteotsunami from being modelled as occurring instantly.

• Despite their lower energies, they can be strong enough to cause localised damage and loss of life on shorelines where they can be intensified by resonance.

Types of Tsunami

There are three basic types of tsunami that occur worldwide. Let us discuss in detail the types of tsunamis in this article on tsunami.

Local Tsunami

• A local tsunami is one that causes damage in close proximity to the event that triggered the tsunami.

• The underwater occurrence, which is typically an earthquake that triggers a local tsunami, occurs within 100 kilometres (just over 60 miles) of the land damage that results.

• Since the time between the underwater occurrence and the arrival of the tsunami can be less than an hour, and even less than 10 minutes, these tsunamis can be catastrophic.

• There is insufficient time to perform a thorough evacuation.

Regional Tsunami

• A regional tsunami is described as one that causes damage between 100 and 1,000 kilometres from the source of the tsunami. Outside the 1,000-kilometer perimeter, more contained damages will occur in some cases.

• Regional tsunamis have a significantly longer warning time than local tsunamis, arriving between one and three hours after the triggering incident.

• Within a 1,000-kilometer radius, one to three hours might not be enough time for people to safely evacuate.

Distant Tsunami

• A distant tsunami, also known as a Teletsunami or ocean-wide tsunami, is caused by a strong and devastating occurrence that occurs more than 1,000 kilometres away from landfall.

• A distant tsunami may appear to be a local tsunami at first, but it spreads through vast swaths of the ocean basin.

• A distant tsunami allows more time to evacuate and flee, but it also occupies a wider area of land and is more likely to cause extensive and widespread damage.

Effects of Tsunami

• Till now we have learned about what is a Tsunami and the types of the tsunami. So in this section, we will learn about the effects of the tsunami.

• A tsunami’s impact on a coastline can vary from mild to catastrophic. The characteristics of the seismic event that caused the tsunami, its distance from its point of origin, its duration, and, finally, the structure of the depth of water in oceans along the coast that the tsunami is approaching, all influence the effects of the tsunami.

• Here let us discuss a few of the catastrophic effects on nature, animals, and humans.

Destruction

• When a massive tsunami hits land, the amount of energy and water stored in it will cause massive damage.

• Tsunamis inflict damage by two mechanisms: the slamming force of a fast-moving wall of water, and the destructive strength of a large volume of water draining off the ground and bringing a large amount of debris with it, even with small waves.

• The initial wave of a large tsunami is extremely high, but it does not cause the majority of the damage. The vast mass of water behind the initial wavefront causes the majority of the damage, as the sea level continues to rise rapidly and floods the coastal region. 

• The strength of the waves, the never-ending crashing water, is what causes destruction and death. A tsunami’s huge breaking waves will kill everything in their way as they pound the shoreline.

• Tsunami waves wreck everything in their path: boats, houses, bridges, vehicles, trees, telephone lines, power lines, and just about everything else. 

• If the tsunami waves have swept away the shoreline’s infrastructure, they will proceed inland for several miles, sweeping away more trees, houses, vehicles, and other man-made objects. 

• Some tsunamis have also made some of the small islands unrecognisable.

Death

• The cost of human life is one of the most significant and destructive consequences of a tsunami since surviving a tsunami is virtually impossible. Tsunamis claim the lives of hundreds of thousands of people.

• Before a tsunami hits the ground, there is very little warning. When the water flows toward the shore, there is no time to plot an escape path.

• People who live in coastal areas, cities, and villages do not have the luxury of time to flee. The tsunami’s strong force causes instant death, most usually from drowning. Another cause of death is buildings collapse, electrocution, and fires from gas, broken tanks, and floating debris.

Disease

• In tsunami-affected areas, the disease could spread due to flooding and polluted drinking water. When water is stagnant and polluted, illnesses like malaria will spread.

• Since it is difficult for people to remain healthy and diseases to be treated in these environments, infections and illnesses will spread rapidly, resulting in more deaths.

Environmental Impacts

• Tsunamis not only kill humans, but also wipe out insects, livestock, plants, and natural resources.

• The landscape is changed by a tsunami. It uproots trees and plants, as well as animal habitats including bird nesting sites.

• Drowning kills land animals, and waste kills sea animals when toxic substances are washed into the sea, poisoning marine life.

• The environmental impacts of a tsunami include not just the landscape and animal life, but also the man-made elements of the climate.

More Facts About the Tsunami

• The most dangerous tsunami recorded till now is the Boxing day tsunami, also known as the Indian Ocean tsunami with at least 2,30,000 people killed or missing in 14 countries bordering the Indian Ocean, it was one of the worst natural disasters in human history.

• The most recent tsunami is the tsunami 2020 which occurred on the island of Samos (Greece) and the Aegean coast of the Izmir region (Turkey) on 30 October 2020. This significant tsunami was triggered by an earthquake of magnitude 7.0 Mw.

• Some zoologists claim that some animals can detect subsonic Rayleigh waves generated by an earthquake or tsunami. Monitoring their actions, if done correctly, may provide an early warning of earthquakes and tsunamis. The proof, on the other hand, is debatable and not generally accepted.

• About 80% of Tsunami occur in the Pacific Ocean, “Rings of Fire”.

• The first wave of Tsunami is not the strongest. However, the successive waves are stronger and bigger. 

• Tsunamis can travel up to the speed of 805 km/hrs or 500 miles almost as fast as a jet plane.

• The US states like Hawaii, Alaska, Oregon, California, and Washington are at the highest risk of Tsunami.

• If anyone is caught by a Tsunami wave, it’s better to not swim, instead, he must grab an object and let the wave carry him.

• Tsunamis can travel throughout the ocean with minimum energy loss.

• Hawaii is always at risk of a Tsunami- It gets hit by one each year and seven in every seven years. In 1946, Hawaii got hit by the biggest tsunami wave at Hilo Island. The reported height of the wave was 30ft and the speed was 500mph.

• In 2004, an earthquake caused a tsunami in the Indian Ocean with the energy of 23000 atomic bombs. After the earthquake, 11 countries were slammed by the radiation emitted from the epicentre. The total death toll was 283000.

 

Tsunami Safety

A Tsunami becomes dangerous when it approaches land. Its speed decreases from 30mph to 20mph when it enters shallow water near coastlines. The height increases, wavelength decreases, and the currents intensify. Tsunami warnings come in various forms. Tsunami warning centres broadcast warnings through local radio and television, weather radios, wireless emergency alerts, and social media. They may also be received by outdoor sirens, text message alerts, local officials, and telephone notifications.

It is better to recognize natural tsunami warnings instead of waiting for an official warning. These include long and strong earthquakes, a loud sound (similar to train or aeroplane) coming from the ocean, a sudden rise or fall in the sea level not related to the tide. Both natural and official warnings are equally important. One should be prepared to respond quickly to these warnings.

One can move to a safe place by following the evacuation signs. If an individual is unable to do so, then he must go to high ground or far away from the coastlines.

When tsunamis strike land, their height is less than 10 feet, but in some cases, it can exceed 100 feet near their source.

A tsunami can come to the shore like a wall of turbulent water or a fast-rising flood. Moreover, a huge tsunami wave can destroy low-lying coastal areas to a large extent.

Rushing water from floods, waves, and rivers is highly powerful. It can wash off everything coming on their way.

Tsunamis are destructive due to their volume and speed. They become more dangerous when they return from the sea carrying people, objects, and debris with them. Therefore, people are advised to stay out of the tsunami hazard zones until the conditions come under control.

Waterspout meaning is simply its form of Tornado only. For many years they were named tornadoes over water, a definition still in wide use. But actually, it is a little-diameter column of rapidly swirling air in contact with a water surface. Waterspouts are nearly always generated by a space-growing cumulus cloud. They may appear in various forms and often happen in a group, named as the waterspout family, generated by the same upward-moving air current. A waterspout is nearly linked to different atmospheric phenomena such as water tornados, whirlwinds, and firestorms.

History: What is a Spout?

In the past few years, the intense waterspouts have caused deaths when they migrated inland over populated areas, and they absolutely create a threat to small craft. However, there are some authentic cases of large ships being damaged by a spout. The superstition that burning a cannonball or another projectile into a spout does “break it up” has no logical foundation. Contrary to popular belief, a waterspout does not “suck up” water to high heights, though it does lift the water level a meter or so at its point of contact with the surface. It is presumed, but continues unproven, that waterspouts sometimes draw fish and frogs into its vortex and then fall them onto land, thus considering the reported falls of such objects.

Recent scientific interest in waterspouts began with the appearance of an individually high and persistent spout on August 19, 1896. Its height was supposed to be 1,095 meters and its diameter, 256 meters at the peak. The spout’s flow continued for at least 35 minutes, as the noticeable funnel disappeared and re-formed 3 times. 

Define Spout Formation in Different Areas?

While it is usually lower than most of its land counterparts, more powerful versions produced by mesocyclones do occur. Most waterspouts do not absorb up water; they are tiny and light rotating columns of air over water. While waterspouts are often seen in tropics and subtropical areas. Other areas including reported waterspouts are Europe, New Zealand, the Great Lakes, and Antarctica. Moreover rare, waterspouts have been noted in connection with lake-effect snowstorm bands. 

Waterspout Falls into two Categories

Tornadic waterspouts are tornadoes that develop above water or keep shifting from land to water. They have the same characteristics as you can see in a land tornado. They are linked with severe thunderstorms and are often co-occurred by high winds and seas, large hail, and frequent dangerous lightning.

Fair-weather waterspouts usually form beside the dark flat bottom of a line of developing puffy clouds. This kind of waterspout is usually not associated with thunderstorms-like situations. While tornadic waterspouts generate down in a storm, a fair-weather waterspout occurs on the surface of the water and moves its way upward. At the time the funnel is noticeable, a fair-weather waterspout is near seen. Fairweather waterspouts form in light wind situations so they usually move very lightly.

What is a Waterspout Formation Stage?

There are 5 stages of waterspout formation:

1. Dark Spot- The uppermost layer of the water gets on a dark color where the waterspout, or column of rotating wind, outstretches it.

2. Spiral Pattern- Light and shaded bands spiral out from the dark spot.

3. Spray Ring- A swirling circle of sea spray called a waterfall forms throughout the dark spot. It seems to have an eye at the center, alike to that seen in a storm.

4. Mature Vortex- The waterspout is now at its usual intense stage, noticeable from the surface of the water to the clouds overhead. It seems to have a hollow funnel and may be enclosed by vapor.

5. Decay- When the stream of warm air into the vortex loses, the waterspout falls.

The medium waterspout is about 50m that is 165 feet in diameter. With wind speeds of 80km per hour corresponding to the lowest types of tornadoes on land. The most extensive waterspouts do have widths of 100m that is approximately 330 feet and continue for up to 1 hour, though the common record is of just 5- 10 minutes. 

Waterspout Safety Measures

Regardless of what kind of waterspout it is, fair weather or tornadic in origin, all sea-going ships must take care.

• Do not navigate within a waterspout or move closer to it for investigation.

• To avoid a waterspout, try going at right angles to its clear direction of movement.

• Darks spots on the water, accompanied by rings or a swift shift in wind can be warning indications of a growing waterspout.

They are not as critical as their land-based counterparts; the tornado or twister, but care need to be taken care of when finding one of these natural occurrences.

Andesite is an extrusive volcanic rock. It is an intermediate type between basalt and rhyolite. It is fine-grained in texture and is sodium-rich plagioclase and pyroxene or hornblende. The dominant rock type in island arcs is also known as Andesite. The average composition of the Earth’s crust is andesitic. They are major components of Martian Crust. The name andesite is derived from the Andes mountain range where this rock is found in abundance. 

Andesite Description

A rock that has a medium level of silica and lesser amounts of Alkali metals is Andesite rock. It is also fine-grained. It consists of less than 10% feldspathoid by volume. Andesite is distinguished from basalt by its silica content of over 52%. It is further not possible to determine the mineral composition of volcanic rocks, due to their fine grain-like texture. Andesite is defined chemically as a volcanic rock with a content of 57% to 63% silica. It does not consist of more than 6% alkali metal oxides.

It is usually light to dark grey in color due to its content of pyroxene minerals. It exhibits a wide range of shading. Darker andesite is usually difficult to distinguish from basalt. A common rule of thumb is used, it states when used away from the laboratory, andesite has a color index less than 35.

Porphyritic andesite is another variation that contains larger crystals of plagioclase formed prior to the extrusion in a finer-grained matrix. These minerals have the extreme melting temperatures of the typical minerals that can crystallize from the melting lava. These are usually the first to form solid crystals. Andesite porphyry is the general name that is used for these rocks with two different crystal sizes.

The plagioclase in andesite varies widely in sodium content from anorthite to oligoclase, but it is typically andesine. The mineral included in andesite is augite, pigeonite, or orthopyroxene. 

Andesite Rock 

Andesite rock description or andesite description type falls under the Igneous rock. The lava  that forms Andesite rock has moderate viscosity forming thick lava flow as well as domes. Andesite is the volcanic equivalent of diorite. It contains silica mainly between 52% – 63%. It is used as an aggregate or to fill. Usually used in the construction and roading industries. It is often not ideal for concrete aggregate because of high silica content. 

Above subduction zones are found Andesite and diorite rocks that have continental crusts. They usually form after an oceanic plate melts. The plate melts during its descent. It produces a source of magma. Diorite forms when magma remains below Earth’s surface and cools slowly. Andesite is a fine-grained rock that forms when magma erupts onto the surface and crystallizes quickly. 

Both Andesite and Diorite have a composition that is intermediate between basalt and granite. The parent magmas formed due to partial melting is the reason behind it.  The partial melting is of the basaltic oceanic plate. This magma receives a granitic contribution by melting granitic rocks. They are ascended or mixed with granitic magma.

Andesite Thin Section

A thin section of rock is prepared by gluing a small piece of rock onto a glass slide. It is then ground down to a thickness of 30 microns. It is done so that light shines through it when examined under the microscope. 

Banded iron formation also shortly known as BIF is a major source of iron. BIF is a rock type made up of substituting silica- and iron-rich bands. BIF is economically among the most significant rock types as our society is largely dependent on iron, which is principally extracted from this rock. Photosynthetic organisms that were producing oxygen, but reacted with the iron dissolved in seawater to create iron oxide minerals on the ocean floor, ended creating banded iron formations.

Composition of Banded Iron Formation

Banded iron formation contains layers of iron oxides (essentially either hematite or magnetite) isolated by layers of chert (silica-stocked sedimentary rock). Each layer is generally narrow (millimeters to few centimeters). The rock has a characteristically banded appearance due to differently colored darker iron-rich and lighter silica layers. In some cases BIFs may consist of siderite (carbonate iron-carrying mineral) or pyrite (sulfide) instead of iron oxides and in place of chert the rock may consist of carbonaceous (rich in organic matter) shale.

BIF is a chemogenic sedimentary rock (material thought to be chemically catapulted on the seafloor). Since old age BIFs usually have been metamorphosed to a different degree (particularly older types), but the rock has heavily retained its original appearance since its constituent minerals are reasonably stable at higher temperatures and pressures. These rocks can be defined as metasedimentary chemogenic rocks.

Types of Banded Iron Formation

BIFs formed in three episodes i.e. 3500-3000 Ma (millions of years ago), 2500-2000 Ma, and 1000-500 Ma. The BIFs from these three episodes are known as Algoma-, Superior- and Rapitan-types, respectively. In each case there were several simulations that resulted in their formation.

1. Algoma

Algoma-type is the oldest (from the Archaean) and appears to be linked with volcanic arcs. They are majorly found in old greenstone belts. Iron-rich minerals are customarily magnetite. Algoma-type iron ore bodies are comparatively small, generally less than 100 meters in thickness and several kilometers in lateral extent. Algoma-type accumulations are mined in the Bjørnevatn (Norway), Abitibi greenstone belt (Ontario, Canada), Kostomuksha (Russian Karelia), etc.

2. Superior

So far it is also one of the significant types of banded iron formations formed during the Paleoproterozoic (Superior-type). They formed on firm continental shelves. Superior-type accumulations are in vast dimensions (greater than 100 meters in thickness and over 100 km in lateral extent). A crucial iron-bearing phase is hematite, but magnetite also occurs. Iron mines where BIFs pertains to Superior-type include Lake Superior (Canada, USA), Labrador (Canada), Hamersley Basin (Australia), Kryvyi Rih (Ukraine), and Transvaal Basin (South Africa), Quadrilatero Ferrifero (Brazil), Singhbhum (India).

The ocean was also a profuse source of silica to form chert layers since the seawater is thought to have been saturated with silica (120 mg/l) during most of the Archaean-Proterozoic.

3. Rapitan

This type is the least significant with respect to the volume of ore mined. Their genesis appears to be linked with glaciations, global ice age (Snowball Earth) and related environmental changes. Iron-bearing mineral in Rapitan-type accumulations is hematite1.

The world ocean was almost completely overlaid ice and thus separated from the atmosphere. That reintroduced diminishing conditions in the water column same as those that existed before the oxygenation of the atmosphere. This near global anoxia in seawater is usually perceived to be the reason why BIFs reappeared as iron deposited in the water and were later accumulations when the ice age subsided and the ocean was oxygenated again.

Problem With Banding of BIFs

Another key issue is the banding of BIFs. These bands could display seasonal cycles as modern varves do. Or it could be some other major cyclical alteration in ocean water chemistry or biology. It appears possible that there was some form of biological mediation and the alterations in BIF composition display the cyclical changes in the numbers of organisms.

Fun Facts

• You can spot a 2.1 billion year-old rock with BIF formation at the National Museum of Mineralogy and Geology, Dresden, Germany.

• Approximately a 3-billion-year-old BIF from Canada reveals that the atmosphere and ocean once had no oxygen.

• Various controversies exist over BIF origination, and many theories have been proposed.

• Banded iron formations, although widely mined, remain mysterious in several ways.

• Understanding of their genesis is largely obstructed by the fact that there are no modern analogues.

• As per a theory, BIF formation has been distinguishably ascribed to volcanic activity; rhythmic accumulation from iron and silica solutions because of oxidation, seasonal variations; and precipitation from solution as an outcome of unique oxidation-reduction conditions.

• All these terms (Algoma, Superior, Rapitan) implies localities in Canada, but they are used to classify BIFs worldwide.

Cassiterite which is also known as tinstone is a heavy, metallic hard tin dioxide(SnO₂) that is the major ore of tin. Cassiterite is colorless when it is pure but turns to brown or black when the iron impurities are present. It is generally opaque but is also translucent in thin crystals. Throughout ancient history, cassiterite was the chief tin ore and even to the present day, it remains the most important source of tin. Cassiterite also occurs in granites and pegmatites.In the fifteenth century, the cassiterite veins present in Saxony and Bohemia were mined for tin and the production of tin was at its peak at the same place in the seventeenth century. In the eighteenth century and the nineteenth century, the very large vein deposits of Cornwall were the major source of tin. In the present day, most of the world’s cassiterite has been mined in Indonesia, Bolivia, Malaysia, Nigeria, Myanmar, Thailand, and other major parts of China. In this article on cassiterite, we are going to discuss what is cassiterite, cassiterite ore, its occurrence, and its physical properties.

 

What is Cassiterite? 

Cassiterite name has been derived from the term Cassiterides which in pre-Roman times was applied for ‘islands off the western coast of Europe’.Cassiterite is a tin oxide mineral and it is considered to be the most significant source of tin and most of the world’s supply of tin is derived by mining out cassiterite. Cassiterite chemical composition is SnO₂. Throughout the world, small amounts of primary cassiterite are found in igneous and metamorphic rocks. Cassiterite is also the residual mineral that is found in solid and sediments. It has been shown that cassiterite is more resistant to weathering when compared to other minerals and as a result of this reason, cassiterite in nature is concentrated in the streams and shoreline sediments. Cassiterite is the most important ore of tin and despite that its concentration is high in only a few locations. Cassiterite has been found in the hydrothermal veins and pegmatites which are associated with granite intrusions. 

Occurrence of the Cassiterite Ore 

•  The primary source of cassiterite ore which is worth mining is found in the high-temperature hydrothermal veins that companies granitic intrusions. 

• The alluvial or the placer deposits which contain the resistant weathered grains is considered to be the main source of cassiterite in today’s world. 

• Along with the deposits of cassiterite, there are also deposits of fluorite, topaz, apatite, and tourmaline. 

• The most important deposits of primary cassiterite ore are found in Brazil, Indonesia, Australia, Bolivia, China, England, The Democratic Republic of Congo, Peru, Portugal, Russia, Spain, and other countries of South Asia. 

• The secondary placed deposits are responsible for producing the world’s most cassiterite. These are sediment-hosted concentrations of cassiterite in stream valleys and along the shorelines. 

•  The hardness of cassiterite allows it to survive the stream transport and its property of high specific gravity causes it to concentrate in the deposits that are large and rich enough for mining. 

• The tin mines of Bolivia are the best source of the primary cassiterite, in the tin mines, the cassiterite is found in the hydrothermal veins. Rwanda has a nascent cassiterite mining industry.

• There are also other high specific gravity minerals that occur in the tin deposits. Deposits if cassiterite is being found in Burma, China, Indonesia, Malaysia. Myanmar, Nigeria, and Rwanda.

• There has been fighting over the cassiterite deposits particularly in Walikale and it is considered to be the major cause of the conflict waged in the eastern part of the Democratic Republic of Congo. Due to this reason cassiterite has been considered as the conflict mineral. 

• The United States of America does not have any major deposits of cassiterite or tin minerals and is heavily dependent on other countries for it. There are small deposits in Alaska, South Dakota, and other states.

• In the present day, the major production of tin comes from placer or the alluvial deposits in Malaysia, Thailand, Indonesia, Russia, and the Maakhir region of Somalia.

Physical Characteristics of Cassiterite

• The Colour of cassiterite is black, brownish-black, reddish-brown, brown, red, yellow, gray, white and  it is rarely colorless

• Transparency: Cassiterite is a very transparent mineral and they are transparent in the thin crystals otherwise are opaque. 

• Cassiterite has a luster that is either greasy or adamantine. 

• The crystal structure of cassiterite is tetragonal. 

• Cleavage is good but in two directions which forms prisms but it is poor on the third side(basal).

• Mohs Hardness of cassiterite is between 6-7.

• Specific Gravity of cassiterite mineral is between 6.8-7.1 which is very heavy for nonmetallic minerals.

• Cassiterite mineral has a high refractive index which is approximately close to 2. 

• Diagnostic properties of cassiterite include high specific gravity, bright metallic to adamantine luster, light streak, and fibrous appearance. 

• The chemical composition of cassiterite is SnO₂, Tin oxide. 

• The cassiterite mineral is used as an ore of tin, a collector’s gem, and a mineral specimen.

• The other minerals that are associated with cassiterite are molybdenite, bismuthinite, topaz, fluorite, arsenopyrite, tourmalines, and wolframite.

• The cassiterite mineral is either infusible or soluble with any other compounds. 

• The primary cassiterite ore is found in places such as England; Durango, Mexico; Malaya; Indonesia; Russia,  China, La Paz, and Colquiri areas of Bolivia and Cornwall

Cassiterite – The Gemstone

Cassiterite is a gem that is very rare to be found. Cassiterite must be transparent, free of fractures, have attractive color, and should have a high clarity to be gem-quality cassiterite. When the cassiterite mineral is cut properly it can be a beautiful gemstone. Cassiterite as gemstone occurs in various colors such as yellow, brown, orange, red, and green. Some gemstones of cassiterite have a strong fire that even rivals that of a diamond. 

Cassiterite as the gemstone is not found in the jewelry stores as it is very rare and that is the reason that there is no demand for it. The cassiterite gemstone is so rare that the adequate amounts required to support a marketing campaign are not available and as a result of this cassiterite is cut mainly for collectors and museum exhibits. 

High dispersion is the one property of cassiterite that makes it an eye-catching gemstone. Dispersion is the ability of any material to separate the white light into separate spectral colors. High dispersion is the property that is responsible for producing the colorful “fire” of a diamond. The dispersion of diamond is about 0.044 whereas the dispersion of cassiterite is 0.71 which is considerably higher than that of a diamond. Due to the high dispersion property of cassiterite, it enables it to produce a fire that exceeds that of a diamond. Cassiterite gemstones which have light colors show a strong fire whereas in many cases the cassiterite with dark color partially masks the fire. 

If you have visited the beach, you must have been on the coast. The cost is also known as coastline, or seacoast is defined as the area where the land touches the sea or oceans. The edges of a coast where the land touches water are known as the coastline. The coastline is formed through waves, tides, and currents. 

Coast enables us to understand natural events such as weather or changing sea levels. During storms, coastal areas are the first place to be flooded the most. The coastal areas, as beautiful as they seem to be, become uneven sometimes as they are highly affected by pollution, garbage, oil spills from both land and sea.

Tourists visit the coast during a vacation to participate in different activities like fishing, swimming, and boating. 

What is the Coastal Range?

The coastal range, also known as the Pacific coast range, is the series of mountain ranges in the United States running alongside the Pacific coast for more than 16000 km or 1000 miles starting from west-central Washington in the north to the Transverse Ranges of California in the south. 

The climate of the coastal range is cool, with dry summers and mild, wet winters in the North. From North to South, both summers and winters in the coastal ranges get steadily dusty or dry and variations in wintertime precipitation rise rapidly. Forests along the coast of Northern California and Southern Oregon are influenced by the giant redwoods while farther inland, there can be seen a mixed forest of conifers and broad-leaved redwood. 

Wildlife in the coast range includes small fur-bearing animals such as weavers, rabbits, muskrats, and bobcats, and large animals such as bears, elk, and deer. This is also the place where the legendary hairy, human-like creatures like ‘barefoot’  are almost seen.

Pacific Coast Range

What is Semper Paratus?

The Latin phrase “ Semper Paratus” means “Always Ready”.  Sometimes abbreviated as Semper P.It is also considered to be the official motto of the United States Coast Guard. A 1928 song of the same name, composed in 1927 by Captain Francis Saltan Van Boskerck is also used as the US Coast Guard’s official March and can be seen on the Organization flag.

The origin lyrics of the 1928 song were written by Captain Francis Saltan Van Boskerk in 1922, at the cabin of USRC Yamacraw in Savannah  Georgia. In 1927, he wrote the music on a beat-up old piano in Unalaska, Alaska.

In 1969, the first line of the chorus song was changed from ” So here’s the US Coast Guard Marching Song: We sing on land and sea” to “We are always there for the call, We play our trust in Thee”

What is NVDC?

NVDC, also known as National Vessel  Documentation Centre is the division of the coast guard responsible for managing the certification and federal registration of commercial and recreational boats in the US. The NVDC maintains a database that includes appropriate information regarding every registered ship. The list is available to the public so that they can look for the boats they know or have an interest in. With this, they can find more detailed information about the ships.

 Did You Know

• The climate of the coastal region is the most moderate in the Pacific Northwest.

• The coastal range is the next home to the rainforest.

• If you will measure the total length of the land where it meets water then you will find it is around 312,000 miles or 502,000 km.

• In the countries like Australia or England, the term coast is sometimes referred to as the seaside.

• The most famous example of coast in Great Britain is Holderness coast near Bridlington.

• Coast Guard National Vessel Documentation Centre (NVDC) registered approximately 23000 vessels for commercial and recreational purposes in U.S. waters.