Gemstone Chart |
Natural Oligoclase Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. Oligoclase is famous for its two gem varieties: Sunstone and Moonstone. Color: green, orange, red, colorless Categories: semi-precious stone Chemical Composition: [Na,Ca]AlSi3O8 Crystal Group: Triclinic Refractive Index: 1.53 - 1.54 Hardness: 6 - 6.5 Density: 2.62 - 2.65 Occurrence: Tvedestrand and Hitero on the south coast of Norway; near Lake Baikal Russia; Ontario, Canada; Tanzania; Kangayam, southern India; France; and in Maine, New Mexico, New York, North Carolina, Pennsylvania, Virginia and Oregon in the USA.
| Natural Phenakite phenakite is a fairly rare nesosilicate mineral consisting of beryllium orthosilicate, It is one of the brightest of the colorless gemstones.Madagascar seems to be the most important source for this rare stone. Color: White Categories: semi-precious stone Chemical Composition: Be2SiO4 Crystal Group: Hexagonal Refractive Index: 1.651-1.696 Hardness: 7.5-8.0 Density: 2.94--2.96 Occurrence: Russia, Madagascar, U.S.A., Brazil, France, Switzerland, Ceylon, E. Africa.
| Natural Prehnite Prehnite is a hydrated calcium aluminum silicate that occurs in a soft yellow-green to apple-green color.It was a rare gemstone, most prehnite is translucent but transparent specimens are sometimes found.While you are unlikely to find it in your local jewelry store, gemstone dealers often have some supply. Deposits are found in South Africa, Australia, China, Scotland and the United States. Color: yellow green, brown, yellow brown, oil green Categories: semi-precious stone Chemical Composition: (CA2Al2SI3O10(OH)2) Crystal Group: Orthorhombic Refractive Index: 1.61 - 1.64 Hardness: 6 Density: 2.80 - 2.95 Occurrence: China, France, U.S.A., Scotland, Australia
| Natural Sillimanite Sillimanite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite is a very rare trimorph and it has a common variety called fibrolite. Color: violet blue, grey green, colorless, brown, green, Categories: semi-precious stone Chemical Composition: Al2OSiO4 Crystal Group: Orthorhombic Refractive Index: 1.658 - 1.678 Hardness: 6 - 7.5 Density: 3.25 Occurrence: France, Madagascar, U.S.A., Sri Lanka, Burma. Kenya
| Natural Triplite Triplite is a rare fluoro-hydroxide phosphate mineral that forms in phosphate rich granitic pegmatites and high temperature hydrothermal veins. The name is from the Greek triplos for triple, in reference to the three cleavage directions. It is a very gemstones and few cut stones have been ever reported. Color: brightly coloured (brown, salmon, flesh-red) Categories: semi-precious stone Chemical Composition: (Mn,Fe2+)2(PO4)(F,OH) Crystal Group: Monoclinic Refractive Index: 1.650 - 1.680 Hardness: 5 - 5.5 Density: 3.44 - 3.90 Occurrence: the Shigar Valley, Pakistan; China; France, Bavaria, Germany; Kimito, Finland; Karibib, Namibia; Maine, and Connecticut, Arizona and Colorado in the United States.
| Natural Zircon Zircon is a mineral belonging to the group of nesosilicates. It is one of the heaviest gemstones, which means that it will look smaller than other varieties of the same weight. Zircon occurs in a wide range of colours,the most popular colour is blue zircon. The wide variety of colours of zircon, its rarity, and its relatively low cost make it a popular collector's stone. Color: Brown, blue, red, orange, white, green Categories: semi-precious stone Chemical Composition: ZrSiO4 Crystal Group: Tetragonal Refractive Index: 1.780-1.984 Hardness: 7.5 Density: 4.00-4.73 Occurrence: Ceylon, Burma,France, Norway, East Africa,Australia, SE Asia.
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