Crystals
Lava
“Lava Stone” • Informal term Usually: Vesicular Basalt / Scoria (mafic volcanic rock) Igneous • Extrusive • Volcanic Textures: Vesicular • Scoriaceous • Amygdaloidal Colors: Black • Charcoal • Reddish‑brown...
Lava
“Lava Stone” • Informal term Usually: Vesicular Basalt / Scoria (mafic volcanic rock) Igneous • Extrusive • Volcanic Textures: Vesicular • Scoriaceous • Amygdaloidal Colors: Black • Charcoal • Reddish‑brown...
Meteorite
Meteorite • Extraterrestrial rock (stone • stony‑iron • iron) Typical age: ~4.56 billion years (solar system vintage) Key features: fusion crust • regmaglypts • metal flakes • chondrules Density: ~3.2–8.0...
Meteorite
Meteorite • Extraterrestrial rock (stone • stony‑iron • iron) Typical age: ~4.56 billion years (solar system vintage) Key features: fusion crust • regmaglypts • metal flakes • chondrules Density: ~3.2–8.0...
Kyanite
Kyanite (a.k.a. Disthene) • Al₂SiO₅ • one of the Al‑silicate polymorphs Crystal system: Triclinic • Habit: bladed, radiating Signature: anisotropic hardness — soft along length, hard across Siblings: Andalusite (low‑P)...
Kyanite
Kyanite (a.k.a. Disthene) • Al₂SiO₅ • one of the Al‑silicate polymorphs Crystal system: Triclinic • Habit: bladed, radiating Signature: anisotropic hardness — soft along length, hard across Siblings: Andalusite (low‑P)...
Ruby
Ruby • red variety of corundum — Al₂O₃ colored by Cr³⁺ Crystal system: Trigonal • Habit: tabular/prismatic hexagonal forms, barrel crystals, granular Mohs: 9 • SG: ~3.99–4.05 • RI: ~1.762–1.770...
Ruby
Ruby • red variety of corundum — Al₂O₃ colored by Cr³⁺ Crystal system: Trigonal • Habit: tabular/prismatic hexagonal forms, barrel crystals, granular Mohs: 9 • SG: ~3.99–4.05 • RI: ~1.762–1.770...
Coprolite
Coprolite • fossilized feces — an ichnofossil (trace fossil) Composition varies: phosphate (fluorapatite) ± calcite, silica (chalcedony/jasper), siderite Mohs: ~3–7 (depends on mineralization) • SG: ~2.2–3.2 • Luster: dull→waxy; siliceous...
Coprolite
Coprolite • fossilized feces — an ichnofossil (trace fossil) Composition varies: phosphate (fluorapatite) ± calcite, silica (chalcedony/jasper), siderite Mohs: ~3–7 (depends on mineralization) • SG: ~2.2–3.2 • Luster: dull→waxy; siliceous...
Malachite
Malachite • Cu2CO3(OH)2 • Copper carbonate hydroxide Crystal system: Monoclinic • Habit: Botryoidal, stalactitic, fibrous, banded Mohs ~3.5–4 • SG ~3.6–4.0 Streak: Light‑green • Luster: Silky to vitreous Reacts with...
Malachite
Malachite • Cu2CO3(OH)2 • Copper carbonate hydroxide Crystal system: Monoclinic • Habit: Botryoidal, stalactitic, fibrous, banded Mohs ~3.5–4 • SG ~3.6–4.0 Streak: Light‑green • Luster: Silky to vitreous Reacts with...