Category: Geography Notes PPT

Garnet is the name used for a huge group of rock-producing minerals. These minerals share a familiar crystal composition and a generalized chemical structure of X₃Y₂ (SiO₄)₃. In that chemical composition, “X” can be Ca, Mg, Fe₂⁺ or Mn₂⁺, and “Y” can be Al, Fe₃⁺, Mn₃⁺, V₃⁺ or Cr₃⁺. Although garnet is often linked with the colour red. The red garnet gemstones can be encountered in almost any colour present and are well- recognized choices for jewellery of all types. That’s wonderful news if you’re in the market for this January garnet birthstone.

              

    

Occurrence of Garnet

These minerals are extensively found across the world in igneous, metamorphic, and sedimentary rocks. Most garnet stones are found near Earth’s surface when a sedimentary rock with greater aluminium content, such as shale, is put through heat and pressure intense enough to form schist or gneiss. Garnet is also found in the rocks of contact metamorphism, lava flows, deep-source volcanic outbreaks, subsurface magma chambers, and the soils and sediments formed when garnet-carrying rocks are eroded.

Chemical Properties of Garnet Stone

The commonly encountered minerals in the garnet group are inclusive of almandine, andradite, grossular, pyrope, spessartine, and uvarovite. They all possess a vitreous luster, a brittle tenacity, a transparent-to-translucent diaphaneity, and a shortage of cleavage. They can be found as solitary crystals, stream-tattered pebbles, granular aggregates, and gigantic occurrences. Their chemical structure, hardness, colours and specific gravity are listed below.

Garnet Mineral

Physical Properties of Garnet

Uses of Garnet Mineral

Following are the uses of garnet stone:-

• abrasive blasting granules

• abrasive grits and powders

• Filtration granules

• Waterjet cutting granules

• Gemstones (such as garnet birthstone, garnet earrings).

Garnets Gemstones

Garnet as gemstones has been in use for over 5000 years. It has been encountered in the jewellery of different Egyptian burials and was the most prominent gemstone of Ancient Rome. It is an alluring gem which is generally sold without treatment or enhancement of any kind. It is also durable and common that it can be used in jewellery as garnet earrings, garnet rings etc at a relatively low cost.

Even until now, garnet continues to be a popular gemstone of contemporary times. It caters to as a birthstone for the month of January and is a long-established gem given on a second anniversary.

 

Garnet Varieties

1. Almandine

A frequently found gemstone in the garnet family, almandines come in a huge array of colours. The mix of almandine-pyrope is the dark red variety customarily linked with garnets.

2. Andradite

One of the rarest garnets, these have the highest dispersion of all garnets, even greater fire than diamond. Demantoids, a variant of andradite, are particularly treasured.

3. Grossular

In contrast to other garnets in the family, grossulars are rarely red or even dark. However, they do form in every colour, even colourless, only other than blue. Their vibrant colours make them remarkable jewellery stones. Tsavorites contain an emerald-like green colour and can be a directive of high prices.

4. Hydrogrossular

Never transparent, these are often blueish green in colour. However, Hydrogrossular garnets are sometimes also found in white, pink, and grey.

5. Pyrope

Chrome pyropes display a red that can rival rubies. However,  pyrope garnet stones have a very dark tone.

Fun Facts

• The garnet family is one of the most in the gemological world.

• Although garnet is frequently linked with the colour red, these gemstones can be found in almost any colour and are preferred choices for jewellery of all types.

• Garnet is believed to be a red gemstone; however, it occurs in a variety of colours.

• Gem-quality garnets precipitate in every colour – with red being the most common and blue garnets being particularly rare.

Halite, also known as common rock salt, is a naturally occurring sodium chloride (NaCl) compound. Halite can be found in beds ranging in thickness from a few metres to over 300 metres (1,000 feet) thick on all continents. Evaporite deposits, so named because they are formed by the evaporation of salt water in partially enclosed basins, are typically found with limestone, dolomite, and shale beds. Halite can also be used as a sublimation product in volcanic areas, as an efflorescence in arid areas, and as an evaporation product near salt springs. As in salt domes and diapirs, deformation of halite beds may result in the extrusion of salt plugs through the overlying sediment. To put it another way, Halite is the mineral term for the substance we all know as “salt.” Its chemical name is sodium chloride, and “rock salt” refers to a rock that is mainly composed of halite.

How Does Halite Mineral Form?

Halite is primarily a sedimentary mineral that occurs in arid environments where ocean water evaporates. However, several freshwater lakes, such as North America’s Great Salt Lake and the Dead Sea between Jordan and Israel, are currently forming halite. Several massive salt deposits have accumulated over geologic time as a result of regular episodes of seawater evaporation in constrained basins. These deposits can be tens of thousands of feet deep. Salt domes can develop when they are buried deeply.

Halite can also be found in non-arid areas, in the form of underground deposits that can reach great depths. Drilling wells into the salt layer and taking in hot water to easily dissolve the salt into a brine is a popular method of mining underground Halite deposits. The brine is drained out after it has been coated with dissolved salt. The brine evaporates, leaving behind crystallised salt that can be harvested. The majority of commercially available Rock Salt is regrown from evaporated salt brine, not natural crystals. Evaporation at salt springs, where salty water falls out of the ground in a salt deposit and precipitates as rounded globular masses, also produces halite.

Salt is pushed upwards by an underground force through the soft ground in some underground salt deposits, forming arched structures known as salt domes. These deposits, which are very special geological formations, are also significant sources of salt mining operations.

Physical Properties of Halite Rock

1. Halide is a chemical classification.

2. Color, When pure, colorless or white; impurities contain a variety of colours, including yellow, green, black, brown, and red.

3. Vitreous lustre.

4. Transparent to transparent diaphaneity. 

5. Cleavage is Perfect, cubic, three right-angle directions

6. Diagnostic Characteristics: Cleavage, solubility, and salty taste (Taste testing is not recommended.) Some minerals are poisonous or tainted as a result of other people’s consumption.)

7. Chemical Composition is NaCl.

8. The Crystal System is Isometric.

9. Winter road treatment, a source of sodium and chlorine for chemical processes, food processing, and seasoning are only a few of the applications. In the section below, we’ll go through each use in detail. 

Uses of Halite Rock

Salt is widely used in cooking as a taste enhancer and in the curing of a number of foods, including bacon and fish. Various cultures use it in food storage processes. Larger bits may be ground in a salt mill or dusted over food as finishing salt with a shaker.

Halite is also commonly used to manage ice in both residential and public conditions. Since brine (a mixture of water and salt) has a lower freezing point than pure water, placing salt or saltwater on ice that is below 0 degrees Celsius (32 degrees Fahrenheit) can cause it to melt — this is known as the freezing point depression. After a snowstorm, it’s normal for homeowners in colder climates to spread salt on their sidewalks and driveways to melt the ice. It is not necessary to use so much salt that the ice melts completely; instead, a small amount of salt can soften the ice, allowing it to be easily extracted using other methods. Several cities will spray a mixture of sand and salt on roads before and after a snowstorm to improve traction. Salt brine is more effective than dry salt because moisture is needed for the freezing-point depression to work, and wet salt sticks to the roads better. Otherwise, the salt would be washed away by traffic.

Rock salt is occasionally used in cultivation in addition to de-icing. Inducing salt stress to suppress the growth of annual meadow grass in turf development is an example of this. Other methods include submerging weeds in salt water to dehydrate and destroy them, preventing them from harming other plants. Salt is also used as a cleaning agent in the home. Its coarse design enables it to be used in a variety of cleaning situations, including grease/oil removal, stain removal, and drying and hardening sticky spills for easier cleanup.

For different dishes, some cultures, especially in Africa and Brazil, prefer a wide variety of different rock salts. Pure salt should be avoided because different shades of salt signify the presence of various impurities. Many recipes call for specific types of rock salt, and imported pure salt is often tainted to suit local tastes. Salt was once used as a source of currency in barter systems, and it was solely under the control of authorities and their appointees. The practice of salting the earth was used by some ancient civilizations to make captured enemy land infertile and inhospitable as a form of dominance.

Distribution of Halite Rock

• Hallstatt, Salzburg, and Hall, near Innsbruck, Tirol, Austria. From the Swiss town of Bex in the canton of Vaud.

• In Saxony-Anhalt, Germany, from Stassfurt-Leopold Hall, 34 kilometres south of Magdeburg.

• Big crystal deposits at Wieliczka (Galicia) and Bochnia, Poland. Sicily, Italy, Girgenti and Racalmuto

• In Punjab, India, on the Salt Range.

• In the United States, large crystals at the Potash Corporation of America mine, Carlsbad potash district, Eddy County, New Mexico; various salt domes along the Gulf Coast; and the Permian Basin of Texas and New Mexico; large crystals at the Potash Corporation of America mine, Carlsbad potash district, Eddy County, New Mexico.

Pink Halite

Pink Halite is a type of Halite that has had bacteria from various algae species taint its colour. Halite is a common mineral found near oceans and salt lakes and is regarded as the “natural type of salt.” The masses and tubular crystal structure of this stone can be found.

Conclusion

Halite can be found in beds ranging in thickness from a few metres to over 300 metres (1,000 feet) thick. Halite is primarily a sedimentary mineral that occurs in arid environments where ocean water evaporates. Several freshwater lakes, such as North America’s Great Salt Lake and the Dead Sea between Jordan and Israel, are currently forming halite. Drilling wells into the salt layer and taking in hot water easily dissolves the salt into a brine. The brine is drained out after it has been coated with dissolved salt. The majority of commercially available Rock Salt is regrown from evaporated salt brine, not natural crystals. Evaporation at salt springs, where salty water falls out of the ground in a salt deposit and precipitates as rounded globular masses, also produces Halite. Halite is also commonly used to manage ice in both residential and public conditions. Salt brine is more effective than dry salt because moisture is needed for the freezing-point depression to work. Rock salt is occasionally used in cultivation in addition to de-icing. Pure salt should be avoided because different shades of salt signify the presence of various impurities. The practice of salting the earth was used by some ancient civilizations to make captured enemy land infertile and inhospitable as a form of dominance.  Many recipes call for specific types of rock salt, and imported pure salt is often tainted to suit local tastes. For different dishes, some cultures, especially in Africa and Brazil, prefer a wide variety of different rock salts.

We have all seen the eruption of volcanoes on television or computers. With the eruption of the volcanoes, lava starts flowing on the surface. Magma is usually a molten rock liquid that is found below the surface when the crust of the earth melts. The formation of igneous rocks starts taking place when the molten lava or magma begins to cool down and solidify. Igneous rock meaning relates to the solidification process that leads to the creation of rocks. The features of the igneous rock can be identified by its texture, mineral composition, density, and colour. These rocks are formed either with or without crystallization. 

Cooling Process of Igneous Rock

In the intrusive igneous rock, the process of cooling is usually slow that allows the growth of large mineral crystals within the rocks. The feature of igneous rocks having coarse minerals is due to the crystals of the intrusive rocks. Examples of igneous rocks include granite, peridotite, diorite, and gabbro. 

Next comes the extrusive type of igneous rocks that don’t allow crystallisation to take place. Thus, the final appearance is the fine-grained, glassy and vesicular rock formation. Examples of igneous rocks in the extrusive category include basalt, andesite, and rhyolite. 

Types of Igneous Rocks

The igneous rocks definition includes two categories of rock formation. These two types are discussed below in detail. 

Intrusive Igneous Rocks: When the molten lava cools slowly below the earth’s surface, the crystallization results in the formation of large crystals. These typically have a large amount of silica content within them and based on it they are known as diorite, gabbro, pegmatite, and granite. Actually, most of the magma available in the crust is never able to reach the earth’s surface. 

Extrusive Igneous Rocks: The extrusive igneous rocks are also known as volcanic rocks due to their formation from volcanoes. During the volcanic eruption when the magma reaches the earth’s surface, these are known as lava or volcanic rocks. The features of the igneous rocks in the extrusive category also have a silica content in a higher amount. Some of these rocks cool down so instantly that these form an amorphous glass. Examples of extrusive igneous rocks are basalt, pumice, tuff, etc. 

Types of Magma and Formation of Igneous Rocks

There are types of magma and these igneous rocks meaning comes from the type of magma they originate from. We will see the classification and properties of igneous rocks based on the magma. 

Intermediate Igneous Rocks: The composition of magma between felsic and mafic leads to the formation of intermediate igneous rocks. These are typically formed in the subduction zones that also include the oceanic plates. The structure of the rock includes examples like feldspar, pyroxene, biotite, quartz, and amphibole. 

Ultramafic Igneous Rocks: The characteristics of igneous rocks are mainly ferromagnesian and olivine in nature. For example, a slow cooking rock peridotite is a perfect example in this category. These igneous rocks cool down very slowly and are rare in nature. 

Mafic Igneous Rocks: When magma cools down, the ferromagnetic minerals dominate this type of rock formation. Typically, it is found prevalent in oceanic divergent zones. It contains minerals such as magnesium and iron silicate. Moreover, these rocks also have other minerals like olivine, pyroxene and others.

Felsic Igneous Rocks: This rock formation by magma contains aluminium and silicon. The formation takes place in the continental crust having high gas content. Besides, it also has mineral contents like biotite, quartz, potassium, and more. Examples of rock in this category include rhyolite and granite. 

Identification Process of Igneous Rocks

What we generally understand by the meaning of igneous rocks is that it is formed from the cooling and solidification of molten rocks or magma. When the molten lava starts to cool a new layer of minerals and textures are formed with the addition of new chemical components surrounding the rocks. The pressure and temperature at which the lava begins to cool and the time is taken depends on several factors. Due to this, we can see every igneous rock vary in its texture and composition. However, it is the textural and compositional properties that help us to identify the igneous rocks and determine the cooling process and magma formation. 

Did You Know

The first type of rocks formed on the earth surface was igneous rocks. These are also known as the primary rocks. 

Jadeite is a pyroxene mineral with the chemical formula NaAlSi₂O₆. It has a single axis. Depending on the composition, it has a Mohs hardness of 6.5 to 7.0. The mineral has a specific gravity of about 3.4.

The name jadeite is derived from the Spanish phrase “piedra de ijada,” which means “stone of the side”. The term nephrite is derived from the Latin version of the name, lapis nephriticus, which is a different mineral from the common name jade.

Jadeite Stone Chemistry

Other pyroxene end members that form solid solutions with jadeite include augite and diopside (CaMg-rich endmembers), aegirine (NaFe endmember), and kosmochlor (NaCr endmember). Omphacite is a type of pyroxene that contains both the jadeite and augite endmembers. Jadeite forms in metamorphic rocks under high pressure and relatively low temperature. Albite (NaAlSi₃O₈) is a common mineral in the Earth’s crust with a specific gravity of about 2.6, which is significantly lower than that of jadeite. Albite degrades under increasing pressure to form the high-pressure assemblage of jadeite and quartz.

Jadeitite refers to rocks that are almost entirely composed of jadeite. Jadeitite appears to have formed from subduction zone fluids in association with serpentinite in all well-documented occurrences. Jadeitite is resistant to weathering, and boulders of jadeitite formed in serpentine-rich environments can be found in a variety of environments.

Jadeite Stone Colour

The colour of jadeite typically ranges from white to pale apple green to deep jade green, but it can also be blue-green (as in the recently rediscovered “Olmec Blue” jade), pink, lavender, and a variety of other rare colours. Chloromelanite is a dark green to black mineral. The presence of trace elements such as chromium and iron has a large impact on colour. Its transparency ranges from opaque to nearly clear. Colour and translucency variations are common even within a single specimen.

Where is Jadeite Found?

Jadeite has been found in California, the United States, Myanmar, New Zealand, Guatemala, and Itoigawa, Japan; other jadeite locations include Kazakhstan, Russia, British Columbia, Canada, Italy, and Turkestan.

What is Imperial Jade?

Originally, it was assumed that all jade objects were made of the same material. However, in 1863, a Frenchman named Alexis Damour discovered that “jade” could be separated into two minerals: jadeite(imperial Jade) and nephrite.

The mineral compositions of jadeite and nephrite are markedly different. Nephrite is a magnesium-rich amphibole, whereas jadeite is aluminium-rich pyroxene. However, in the eyes of the average person, the two minerals have very similar physical properties.

Physical Properties of Jadeite and Nephrite

What is Jadeite Used for?

Over 180 axe heads made from jadeitite quarried in northern Italy during the Neolithic era have been discovered across the British Isles. Due to the difficulty of working this material, all of the axe heads found are thought to be non-utilitarian and to have represented some form of currency or be the products of gift exchange.

Many jadeite beads and axe heads, as well as the remains of Neolithic jadeite workshops, have been discovered in Itoigawa, Japan. These beads and axes were traded throughout Japan and the Korean Peninsula and were made by the Itoigawa region’s oldest known jadeite-using culture.

Litharge is a kind of mineral that is mainly used to manufacture Lead Stabilizers, Lead glass, pottery, paints, inks, and enamels. This is Lead Mono-Oxide, reddish or yellowish and heavy, reddish, earthy, odourless, solid, and water-insoluble. The other common names of this chemical component are Lead Oxide, Yellow Oxide, Plumbous Oxide, and commonly Lead Monoxide. At times Litharge is also known by its name Lethargic.

Formation of Litharge

This chemical is a secondary mineral that is formed from the oxidation of the galena ores. The mineral is formed as encrustations and coatings that are formed with the internal crystalline structure of tetragonal. The chemical components of Litharge give it a soft and greasy texture that contains a very high-specific gravity ranging between 9.14-9.35. One can also prepare PbO by heating lead metal at an approx. The temperature of 600˚C.

The preparation setup includes a pumping air on the molten Lead that will cause the oxidized mineral to fall off the top into a container where it gets solidified in minutes. Esper S. Larsen Sr. originally established Litharge as a polymorph of massicot and was supposedly identified as a new mineral in 1917. 

Composition of Litharge Formula

Types of Litharge

Out of hundreds of inorganic and organic lead compounds, including carbonates, oxides, sulfates, silicates, chromates, and acetates, Litharge is the most important of all. Lead Monoxide or Litharge consists of roughly 93% of Lead and only 7 % of oxygen as per weight. The process in which it is made yields a very distinctive variation of the physical properties. This makes it available in many particle sizes and only two crystal forms. 

When blended with red Lead and other combination additives, it yields a paste-type material used in the storage of batteries. The highest purity litharge is widely used in various crucial things like TV picture tubes, glass production, computer display terminals, etc. Litharge of Gold is formed when Litharge is mixed with red Lead, and Litharge of silver is formed as a by-product when silver is separated from Lead. Also, there is a Litharge of Bismuth obtained as a result of the oxidation of Bismuth. The two industrial forms of Litharge are Granular Litharge and Litharge powder. Litharge for sale is available in these mentioned variants.

Uses of Litharge

The heavy yellow powder, a product of Lead monoxide, Litharge, has several benefits and uses in the industrial arena. Litharge is hugely used as a red paste material for the storage of batteries derived from a blend of Red Lead and Litharge with other additives. Besides that,

• The most superior quality Litharge is extensively used in the production of glass that includes the TV picture tube and computer video display terminals. This is because of Lead’s high shielding capacity that blocks harmful radiation. Commonly, the inner part of a light bulb is made up of leaded glass.

• Litharge has immense use in the manufacture of enamels and the production of frits.

• Also, in the finest crystal glassware, the Lead present in Litharge imparts strength and brilliance.

• Red Lead is also used in various explosives industries, ceramics, paints, and pigments. 

Historical Terminology of the Chemical Name of Litharge

The chemical name of Litharge has its origin from Latin Lithargyrus, which is derived from the combination of lithos (stone) + arguros (silver). As a matter of fact defines, Litharge meaning is the mineral residue after silver is refined. Litharge is a term that is also used as a synonym for red Lead and white Lead. 

The Properties of Litharge Formula are Provided in the Tabular Form:

Physical Properties of Litharge

The earliest illustrations, hence far unearthed, that are indisputably portrayals of land characteristics are the Babylon or Babylonian tablets; certain land drawings found in Egypt and paintings found in early tombs. It is highly possible that these two civilizations evolved their mapping skills roughly simultaneously and in similar directions. Both were crucially related to the fertile areas of their river valleys and thus doubtless made 4r explorations and plats momentarily settled communities were established. Later they structured plans for building of roads, canals, and temples—the correspondent of today’s engineering plans.

Tablet in Iraq

A tablet discovered in Iraq exhibits the Earth as a disk encompassed by water with Babylon as its centre. Apart from this illustration, dating from about 1000 BCE, there seem to have been rather some attempts by Egyptians and Babylonians to display the type and extent of the Earth as a whole. Their mapmaking has been preoccupied with more practical needs, such as the inception of boundaries. Not before the time of the Greek geographer-philosopher did postulation and conclusions as to the nature of the Earth start to take form.

Greek Maps and Geography

The Greeks were superlative among communities of the ancient world for their pursuit and evolution of geographic comprehension. The deficit arable land in their own area resulted in maritime exploration and the evolution of commerce and colonies. By 600 BCE Miletus, on the Aegean, had transformed as a centre of geographic comprehension, and also cosmographic speculation.

Hecataeus’ Map of the World

Hecataeus, a scholar of Miletus, possibly generated the first book on geography in around 500 BCE. A generation afterwards of Herodotus, from more widespread studies and wider travels, stretched upon it. A historian accompanied by geographic leanings, Herodotus documented, among other things, an early orbit of the African continent by Phoenicians. He also enhanced upon the representation of the shape and degree of the then-known areas of the world, and he announced the Caspian to be an inland sea, combating the prevailing view that it was part of the “northern oceans”.

Herodotus’ Map of the World

Although Hecataeus has been considered the Earth as a flat disk encompassed by ocean, Herodotus and his followers cross-questioned the concept and lodged a number of other possible forms. As a matter of fact, the scholars and philosophers of the time seem to have been preoccupied for many years with analysis on the nature and extent of the world. Some modern scholars contributed the first hypothesis of a spherical Earth and the idea steadily developed into a consensus over many years. By the mid-4th century, the theory of a spherical Earth was well accepted among Greek scholars, and formulated six arguments to prove that the Earth was, in reality, a sphere. Subsequently after, the idea of a spherical Earth was usually accepted among geographers and other entities of science.

A disciple of Aristotle in about 300 BCE Dicaearchus, had put an orientation line on the world map, running east and west through Rhodes and Gibraltar. Eratosthenes, Ptolemy and Marinus of Tyre, progressively created the reference-line postulation until a reasonably all-inclusive system of meridians and parallels, as well as techniques of projecting them, had been achieved.

Claudius Ptolemaeus Maps and Geography in the Ancient World

Claudius Ptolemaeus (90–168 CE) has been the greatest figure of the ancient world in the advancement of geography and cartography. An astronomer, spent many years surveying the greatest repository of scientific knowledge at the library in Alexandria. His commemorating work, the Guide to Geography was produced in eight volumes.

The eighth volume was amongst the key contributions, consisting of instructions for creating maps of the world and discussions on mathematical geography and other basic principles of cartography. Ptolemy’s map of the world as it was then known marked the summit of Greek cartography and also the compendium of gathered knowledge of the Earth’s features at that time.