Crystals
Lava
Informal rock name Usually vesicular basalt or scoria Extrusive igneous material Frozen volcanic gas bubbles Black, charcoal, brown, and red Vesicular or amygdaloidal texture Landscape, architectural, and lapidary use Rock...
Lava
Informal rock name Usually vesicular basalt or scoria Extrusive igneous material Frozen volcanic gas bubbles Black, charcoal, brown, and red Vesicular or amygdaloidal texture Landscape, architectural, and lapidary use Rock...
Meteorite
Extraterrestrial geological material Mostly fragments of asteroids Stony, stony-iron, and iron groups Oldest solids approximately 4.567 billion years Fusion crust and atmospheric ablation Iron-nickel metal in many types Chondrules, olivine,...
Meteorite
Extraterrestrial geological material Mostly fragments of asteroids Stony, stony-iron, and iron groups Oldest solids approximately 4.567 billion years Fusion crust and atmospheric ablation Iron-nickel metal in many types Chondrules, olivine,...
Kyanite
Aluminum silicate polymorph Al2SiO5 Triclinic crystal system High-pressure metamorphic mineral Strong directional hardness Perfect and good cleavage Blue, green, gray, white, black Rare orange variety Kyanite: Blue Blades Shaped by...
Kyanite
Aluminum silicate polymorph Al2SiO5 Triclinic crystal system High-pressure metamorphic mineral Strong directional hardness Perfect and good cleavage Blue, green, gray, white, black Rare orange variety Kyanite: Blue Blades Shaped by...
Ruby
Red corundum Al2O3 with Cr3+ Trigonal crystal system Mohs 9 No true cleavage Purplish-red to orangey-red pleochroism Marble, amphibolite, and basalt-associated deposits Rutile silk and six-ray stars Natural and laboratory-grown...
Ruby
Red corundum Al2O3 with Cr3+ Trigonal crystal system Mohs 9 No true cleavage Purplish-red to orangey-red pleochroism Marble, amphibolite, and basalt-associated deposits Rutile silk and six-ray stars Natural and laboratory-grown...
Coprolite
Fossilized fecal material Trace fossil and bromalite Phosphatic, carbonate, iron-rich, or silicified Bone, scale, shell, plant, and microfossil inclusions Pellet, segmented, spiral, and irregular forms Occasionally agatized and polishable Evidence...
Coprolite
Fossilized fecal material Trace fossil and bromalite Phosphatic, carbonate, iron-rich, or silicified Bone, scale, shell, plant, and microfossil inclusions Pellet, segmented, spiral, and irregular forms Occasionally agatized and polishable Evidence...
Malachite
Copper carbonate hydroxide Cu2CO3(OH)2 Monoclinic crystal system Mohs approximately 3.5–4 Specific gravity approximately 3.6–4.0 Light-green streak Botryoidal, fibrous, stalactitic, and banded Closely associated with azurite Acid- and ammonia-sensitive Malachite: Copper’s...
Malachite
Copper carbonate hydroxide Cu2CO3(OH)2 Monoclinic crystal system Mohs approximately 3.5–4 Specific gravity approximately 3.6–4.0 Light-green streak Botryoidal, fibrous, stalactitic, and banded Closely associated with azurite Acid- and ammonia-sensitive Malachite: Copper’s...