Labradorite mineral species in the plagioclase series of the feldspar group; triclinic crystal system; chemical composition of plagioclase feldspars varies between NaAlSi3O8 and CaAl2SiO8. Appearance: • Transparent to opaque• Labradorite – typically gray to nearly black bodycolor; also colorless, green, yellow, orange to brown or brownish red• Phenomena: labradorescence,aventurescence; sometimes weak chatoyancy or asterism in […]

Appearance: • Howlite (HOW-lite) is amineral species; monoclinic crystal system; chemical composition Ca2BsSiO9(OH)5• Semi translucent to opaque• White, often with dark gray and black spiderweb matrix• Commonly dyed blue to imitate turquoise or lapis lazuli Identification: • Optic Character: AGG (DR)• Refractive Index: 1.586-1.605 (+.003), spot reading usually 1.59• Birefringence: .019 (usually not detectable)• Pleochroism: […]

Appearance: • Howlite (HOW-lite) is amineral species; monoclinic crystal system; chemical composition Ca2BsSiO9(OH)5• Semi translucent to opaque• White, often with dark gray and black spiderweb matrix• Commonly dyed blue to imitate turquoise or lapis lazuli Identification: • Optic Character: AGG (DR)• Refractive Index: 1.586-1.605 (+.003), spot reading usually 1.59• Birefringence: .019 (usually not detectable)• Pleochroism: […]

Appearance: • Almandite or almandine is a mineral species in the garnet group; cubic crystal system; chemical composition FeAL (SiO4)3• Transparent to semi-translucent (for very dark stones)• Reddish orange to red, slightly purplish red to reddish purple: typically dark in tone Identification: • Optic Character: SR, often ADR• Refractive Index: 1.790 (3.030)• Birefringence: none• Dispersion: […]

Appearance: • Labradorite mineral species in the plagioclase series of the feldspar group; triclinic crystal system; chemical composition of plagioclase feldspars varies between NaAlSi3O8 and CaAl2SiO8• Transparent to opaque• Labradorite – typically gray to nearly black body color; also colorless, green, yellow, orange to brown or brownish red• Phenomena: labradorescence, aventurescence; sometimes weak chatoyancy or […]

Appearance: • Quartz species; hexagonal (trigonal) crystal system; chemical composition SiO2• Rock crystal – transparent colorless Identification: • Optic Character: DR uniaxial positive or AGG (depending on variety)• Refractive Index: 1.544-1.553 (very constant)• Birefringence: .009 (may not be detectable in aggregate varieties) Dispersion: .013• Pleochroism: none• Specific Gravity: 2.66 (+.03.-.02)• Polish Luster: vitreous Fracture: conchoidal […]

Silver Leaf Jasper: • chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2• natural material no any treatment• opaque• green to yellowish green with black, brown, grey stripes• jasper – general variety term applied to semi translucent to opaque chalcedony of any color or combination of colors, except solid black […]

Appearance: • Chalcedony is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2• Semitransparent to opaque• Virtually all colors• Moss agate or mocha stone – chalcedony with green, black, or brown inclusions that look like moss Identification: • Optic Character: AGG• Refractive Index: 1.535-1.539; 1.53 or 1.54 spot reading• Birefringence: usually not detectable, […]

Appearance: • Chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2• Natural material no any treatment• Opaque• Green to yellowish green with black, brown, grey stripes• Jasper – general variety term applied to semi translucent to opaque chalcedony of any color or combination of colors, except solid black or specially […]

Appearance: • Chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2• Semitransparent to opaque• Milky chalcedony – semi transparent to translucent, nearly colorless or white• Natural material no any treatment,  we should call this material “chalcedony”, while always use grey agate to call it in the gemstone business• Agate is […]