Platinum-Group Metals

Platinum, Palladium, Rhodium, Ruthenium, Osmium, and Iridium.
Naturally occurring platinum and platinum-rich alloys have been known for a long time. The Spaniards named the metal "platina," or little silver, when they first encountered it in Colombia. They regarded platinum as an unwanted impurity in the silver they were mining.

The catalytic properties of the six platinum group metals (PGM)– iridium, osmium, palladium, platinum, rhodium, and ruthenium – are outstanding. Platinum's wear and tarnish resistance characteristics are well suited for making fine jewelry. Other distinctive properties include resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum, platinum alloys, and iridium are used as crucible materials for the growth of single crystals, especially oxides. The chemical industry uses a significant amount of either platinum or a platinum-rhodium alloy catalyst in the form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for fertilizers, explosives, and nitric acid. In recent years, a number of PGM have become important as catalysts in synthetic organic chemistry. Ruthenium dioxide is used as coatings on dimensionally stable titanium anodes used in the production of chlorine and caustic. Platinum supported catalysts are used in the refining of crude oil, reforming, and other processes used in the production of high-octane gasoline and aromatic compounds for the petrochemical industry. Since 1979, the automotive industry has emerged as the principal consumer of PGM. Palladium, platinum, and rhodium have been used as oxidation catalyst in catalytic converters to treat automobile exhaust emissions. A wide range of PGM alloy compositions is used in low-voltage and low-energy contacts, thick- and thin-film circuits, thermocouples and furnace components, and electrodes.

Gold

Gold has been treasured since ancient times for its beauty and permanence. Most of the gold that is fabricated today goes into the manufacture of jewelry. However, because of its superior electrical conductivity and resistance to corrosion and other desirable combination of physical and chemical properties, gold also emerged in the late 20th century as an essential industrial metal. Gold performs critical functions in computers, communications equipment, spacecraft, jet aircraft engines, and a host of other products. Although gold is important to industry and the arts, it also retains a unique status among all commodities as a long-term store of value. Until recent times, it was considered essentially a monetary metal, and most of the bullion produced each year went into the vaults of government treasuries or central banks.

Fine jewelry at the lowest price

Diamonds and other stones, gold and other metals, watches, rings and fine jewelry at the lowest price.
According to Mohs' scale, the hardness of--
Talc is 1
Gypsum is 2
Calcite is 3
Fluorite is 4
Apatite is 5
Feldspar is 6
Quartz is 7
Topaz is 8
Sapphire is 9
Diamond is 10
The 16 mineral gemstone groups listed below are highly prized for their beauty, durability, and rarity:

Beryl (hardness: 7.5-8 Mohs)
Beryllium aluminum silicate
Specific gravity: 2.63-2.91

Aquamarine, Brazil
Emerald: Intense green or bluish green
Aquamarine: Greenish blue or light blue
Morganite: Pink, purple pink, or peach
Heliodore: Golden yellow to golden green
Red beryl: Raspberry red
Goshenite: Colorless, greenish yellow, yellow green, brownish

Chrysoberyl (hardness: 8.5 Mohs)
Beryllium aluminum oxide
Specific gravity: 3.68-3.78

Chrysoberyl: transparent yellowish green to greenish yellow and pale brown
Alexandrite: red in incandescent light and green in daylight
Cat's eye: usually yellowish or greenish

Corundum (hardness: 9 Mohs)
Aluminum oxide
Specific gravity: 3.96-4.05

Ruby: Intense red
Sapphire: Blue

Diamond Star of Sierra Leone Diamond (hardness: 10 Mohs)
Carbon
Specific gravity: 3.51

Colorless to faint yellowish tinge, also variable

Feldspar (hardness: 6-6.5 Mohs)
Two distinctly different alkali alumino silicates: the Plagioclase and the Alkali Feldspar Series
Specific gravity: 2.55-2.76

Plagioclase Series-
Labradorite: Colorful, iridescent, also transparent stones in yellow, orange, red, and green
Sunstone: Gold spangles from inclusions of hematite
Peristerite: Blue white iridescence

Alkali Feldspar Group- Orthoclase: Pale yellow, flesh red
Amazonite: Yellow green to greenish blue
Moonstone: Colorless; also white to yellowish, and reddish to bluish gray

Garnet (hardness: 6.5-7.5 Mohs)
A group of silicate minerals
Specific gravity: 3.5-4.3

Almandine: Orangy red to purplish red
Almandine-spessartine: Reddish orange
Andradite: Yellowish green to orangy yellow to black
Demantoid: Green to yellow green andradite
Topazolite: Yellow to orangy yellow
Grossular: Colorless; also orange, pink, yellow, and brown
Tsavorite: Green to yellowish green
Hessonite: Yellow orange to red
Pyrope: Colorless; also pink to red
Chrome pyrope: Orange red
Pyrope-Almadine: Reddish orange to red purple
Pyrope-Spessartine: Greenish yellow to purple
Malaia: Yellowish to reddish orange to brown
Color-change garnet: Blue green in daylight to purple red in incandescent light
Rhodolite: Purplish red to red purple
Spessartine: Yellowish orange
Uvarovite: Emerald green

Jade (hardness: 6 Mohs)

Nephrite
Calcium magnesium silicate
Specific gravity: 2.9-3.1

White, deep green, creamy brown

Jadeite
Sodium aluminum silicate
Specific gravity: 3.1-3.5

White, leafy and blue green, emerald green, lavender, dark blue green and greenish black, deep emerald-green

Lapis lazuli (hardness: 5-5.5 Mohs)
A rock composed mainly of the mineral lazurite with variable amounts of pyrite (brassy flecks) and white calcite
Specific gravity: 2.7-2.9

Deep blue, azure blue, greenish blue (bluish color with flecks of white and gold)

Opal (hardness: 5.5-6.5 Mohs)
Hydrated silica
Specific gravity: 1.98-2.25

White opal: Opaque, porcelain-like white material; colors resemble flashes or speckles
Black opal: Flashes and speckles appear against black background
Water opal: A transparent, colorless opal is the background for brilliant flashes of color
Fire opal: Reddish or orange opal

Peridot [Olivine] (hardness: 7 Mohs)
Magnesium iron silicate
Specific gravity: 3.22-3.45

Olive to lime green

Quartz (hardness: 7 Mohs)
Silicon dioxide or silica
Specific gravity: 2.65

Candelabra: white quartz, blue-capped red elbaite, and tan albite Coarsely crystalline varieties of silica-
Rock crystal: Colorless
Amethyst: Purple
Citrine: Yellow to amber
Morion: Black
Smoky quartz or cairngorm: smoky gray to brown
Rose quartz: Translucent pink
Green quartz or praziolite: Green

Cryptocrystalline varieties of silica-
Chalcedony and Jasper (variable)
Agate: Bull's eye agate, Iris or fire agate, Onyx, Sardonyx. Bloodstone or heliotrope. Carnelian. Chrysoprase. Moss agate. Plasma. Prase. Sard. Jasper.

Spinel (hardness: 8 Mohs)
Magnesium aluminum oxide
Specific gravity: 3.58-4.06

Balas ruby: Red
Almandine spinel: Purple red
Rubicelle: Orange
Sapphire spinel and ghanospinel: Blue
Chlorspinel: Green

Topaz (hardness: 8 Mohs)
Aluminum silicate fluoride hydroxide
Specific gravity: 3.5-3.6

Wine yellow, pale blue, green, violet, or red

Tourmaline (hardness: 7-7.5 Mohs)
Complex aluminum borosilicate
(Elbaite, Dravite, Uvite)
Specific gravity: 3.03-3.25

Achorite: Colorless
Brazilian emerald: Green
Dravite: Brown
Indicolite: Dark blue
Rubellite: Pink to red
Siberite: Violet
Verdilite: Green

Turquoise (hardness: 5-6 Mohs)
Hydrous copper aluminum phosphate
Specific gravity: 2.6-2.8

Sky blue; greenish blue

Zircon (hardness: 7.5 Mohs)
Zirconium silicate
Specific gravity: 4.6-4.7

Jargon: Variable
Matura diamond: Colorless
Hyacinth: Yellow, orange, red, brown