Silicate Mineral Properties
Olivine: SiO4 (Mg,Fe)
Rhombic. Conchoidal, fragile. Olive green, beige, white to gray. Vitreous, translucent to maroon transparent. Hardness 6–7.
Blanca (SiO4)3 A3 B2 cubic, conchoidal, irregular, fragile. Red, reddish black, sometimes pink or purple. Vitreous and resinous, transparent to translucent. Hardness 7.
Andalusite: SiO4 Al AlO (orthorhombic)
Irregular to subconchoidal, fragile. White, gray, red, brown, green. Vitreous, often matte, transparent to translucent. Hardness 7–5. White.
Epidote: Sorosilicate
Green, monoclinic, irregular, fragile. Olive green, gray-green to yellow-green. Vitreous, transparent to translucent. Hardness 6–7. Clear to gray.
Tourmaline: Cyclosilicate, hexagonal
Irregular, conchoidal, fragile....