Crystals
Celestine
Celestine • accepted mineral name; celestite remains a widely used synonym Composition: SrSO4 — strontium sulfate Orthorhombic • barite-group sulfate Mohs 3–3.5 • specific gravity about 3.95–3.97 Perfect basal cleavage...
Celestine
Celestine • accepted mineral name; celestite remains a widely used synonym Composition: SrSO4 — strontium sulfate Orthorhombic • barite-group sulfate Mohs 3–3.5 • specific gravity about 3.95–3.97 Perfect basal cleavage...
Brucite
Brucite • natural magnesium hydroxide • Mg(OH)2 Trigonal structure described in hexagonal axes Perfect basal cleavage • layered octahedral sheets Mohs 2.5–3 • specific gravity about 2.37–2.40 White, green, gray,...
Brucite
Brucite • natural magnesium hydroxide • Mg(OH)2 Trigonal structure described in hexagonal axes Perfect basal cleavage • layered octahedral sheets Mohs 2.5–3 • specific gravity about 2.37–2.40 White, green, gray,...
Blue tiger eye
Falcon’s Eye • Hawk’s Eye • Blue Tiger’s Eye — blue chatoyant quartz with aligned amphibole fibers Principal host: polycrystalline quartz, SiO2 Blue component: comparatively unoxidized riebeckite–crocidolite fibers Optical signature:...
Blue tiger eye
Falcon’s Eye • Hawk’s Eye • Blue Tiger’s Eye — blue chatoyant quartz with aligned amphibole fibers Principal host: polycrystalline quartz, SiO2 Blue component: comparatively unoxidized riebeckite–crocidolite fibers Optical signature:...
Black onyx
Black onyx • straight-banded chalcedony, composed chiefly of microcrystalline quartz with moganite Composition: SiO2 Signature architecture: parallel black, gray, white, or blue-white layers Mohs 6.5–7 • specific gravity about 2.58–2.64...
Black onyx
Black onyx • straight-banded chalcedony, composed chiefly of microcrystalline quartz with moganite Composition: SiO2 Signature architecture: parallel black, gray, white, or blue-white layers Mohs 6.5–7 • specific gravity about 2.58–2.64...
Anthophyllite
Anthophyllite • orthorhombic magnesium–iron amphibole Idealized composition: Mg7Si8O22(OH)2 Iron-rich relative: ferro-anthophyllite Al-rich compositions grade toward gedrite-related amphiboles Cleavage: approximately 56° and 124° Mohs 5.5–6 • specific gravity commonly 2.85–3.2 Habit:...
Anthophyllite
Anthophyllite • orthorhombic magnesium–iron amphibole Idealized composition: Mg7Si8O22(OH)2 Iron-rich relative: ferro-anthophyllite Al-rich compositions grade toward gedrite-related amphiboles Cleavage: approximately 56° and 124° Mohs 5.5–6 • specific gravity commonly 2.85–3.2 Habit:...
Ametrine
Ametrine • natural or synthetic bicolor quartz containing amethyst and citrine-colored sectors Composition: SiO2 with iron-related color centers Colors: violet to purple and yellow to golden orange Crystal system: trigonal...
Ametrine
Ametrine • natural or synthetic bicolor quartz containing amethyst and citrine-colored sectors Composition: SiO2 with iron-related color centers Colors: violet to purple and yellow to golden orange Crystal system: trigonal...