Gold is a chemical element with the symbol Au and atomic number 79.
It is a bright yellow dense, soft, malleable and ductile metal. The properties remain when exposed to air or water. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements, and is solid under standard conditions. The metal therefore occurs often in free elemental (native) form, as nuggets or grains, in rocks, in veins and in alluvial deposits. Less commonly, it occurs in minerals as gold compounds, such as with tellurium as calaverite, sylvanite, or krennerite.
Considered a precious metal with many applications ranging from jewellery, electronics, currency and even medicine.
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The mineral group tantalite [(Fe, Mn)Ta2O6] is the primary source of the chemical element tantalum.
It is chemically similar to columbite, and the two are often grouped together as a semi-singular mineral called coltan or “columbite-tantalite” in many mineral guides. However, tantalite has a much greater specific gravity than columbite. Iron-rich tantalite is the mineral tantalite-(Fe) or ferrotantalite and manganese-rich is tantalite-(Mn) or manganotantalite. Tantalite is also very close to tapiolite.
Those minerals have same chemical composition, but different crystal symmetry orthorhombic for tantalite andtetragonal for tapiolite.
Tantalite is black to brown in both color and streak. Manganese-rich tantalites can be brown and translucent.
Applications for the mineral group are laboratory equipment and as a substitute for platinum. It is also used for medical implants and bone repair. Its main use today is in electronic equipment such as mobile phones, DVD players, video game systemsand computers.
Alexandrite is the rarest of the precious stones and has wonderful qualities that make it sought after.
Alexandrite is the mineral Chrysoberyl. Chrysoberyl can be found in granite rocks, alluvia deposits, pegmatites and mica schist. Most of the Chrysoberyl that is mined is usually found in gavels and river sands.
Antimony is a chemical element with symbol Sb (from Latin: stibium). A lustrous graymetalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were used for cosmetics; metallic antimony was also known, but it was erroneously identified as lead.
Hunan, China has been the largest producer of antimony but now is also found in many other regions.
The largest applications for metallic antimony are as alloying material for lead and tin and for lead antimony plates inlead-acid batteries. Alloying lead and tin with antimony improves the properties of the alloys which are used insolders, bullets and plain bearings. Antimony compounds are prominent additives for chlorine- and bromine-containing fire retardants found in many commercial and domestic products. An emerging application is the use of antimony in microelectronics.
Tungsten, also known as wolfram, is a chemical element with the chemical symbol W. The word tungsten comes from the Swedish language tung sten directly translatable to heavy stone.
A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. Its importantores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements. Also remarkable is its high density many times that of water, comparable to that of uranium and gold, and much higher than that of lead.
Tungsten’s many alloys have numerous applications, most notably in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. About half is used in the form of tungsten carbide, a durable carbon alloy. Tungsten’s hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are also often used as industrial catalysts.
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