Description: Calcite (KAL-site) is a mineral species; hexagonal (trigonal) crystal system. Appearance: • transparent to opaque• almost all colors• phenomena: chatoyancy (in satinspar variety) Variety and Trade Names: • marble – granular aggregate occurring in many colors• onyx marble – banded marble Identification: Optic Character: DR, uniaxial negative; AGG Refractive Index: 1.486-1.658 Specific Gravity: 2.70 (+-.05)Hardness: 3 ; […]
Description: chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system. Appearance: • semitransparent to opaque • virtually all colors Variety and Trade Names: milky chalcedony – semi transparent to translucent, nearly colorless or white• chrysoprase – semi transparent to translucent, light to medium yellowish green (natural color)• carnelian – semi transparent to translucent,yellow-orange to […]
Description: Calcite (KAL-site) is a mineral species; hexagonal (trigonal) crystal system. Appearance: • transparent to opaque• almost all colors Identification: Optic Character: DR, uniaxial negative; AGG Refractive Index: 1.486-1.658 Birefringence: .172Specific Gravity: 2.70 (+-.05)Hardness: 3 ; Toughness: poor in single crystals, fair to good in aggregates Stone Information from: Gem Reference Guide, by GIA, ISBN 0-87311-019-6 Gemstones of […]
Description: Emerald is a variety of the mineral species beryl (BARE-ul); hexagonal crystal system. Appearance: • transparent; highly included stones may be translucent• light to very dark green to very strongly bluish green Identification: Refractive Index: 1.577-1.583 (+-.017)Absorption Spectra: distinct lines at 683 and 680.5 nm, less distinct lines 662 and 646, partial absorption between […]
Description: Aquamarine is a variety of the mineral species beryl (BARE-ul); hexagonal crystal system. Aquamarine (Latin—water of the sea) is so named because of its dark blue is the most desired color. The coloring agent is iron. The most important deposits are in Brazil, other deposits of some commercial significance are in Australia (Queensland), Burma […]
Description: Vitreous luster; sensitive to acids. Deposits in Myanmar, Brazil, India, Kenya, Madagascar, Mexico, Norway, Sri Lanka, South Africa, and the United States. Apatite cat’s-eye is known. Appearance: • transparent to translucent• yellow, green, violet, purple, blue, pink, brown, colorless• phenomena: chatoyancy Identification: Refractive Index: 1.634-1.638 (+.012,-.006)Absorption Spectra: 580 nm doublet common in yellow, colorless, and chatoyant […]
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