Crystals
Epidote
Epidote Group • Ca2(Al,Fe)3(SiO4)3(OH) Monoclinic • Biaxial (+) Mohs ~6–6.5 • SG ~3.3–3.5 Epidote 🌿 — Pistachio‑Green Glow from the Heart of Metamorphic Rocks Vivid green, strongly pleochroic, and a...
Epidote
Epidote Group • Ca2(Al,Fe)3(SiO4)3(OH) Monoclinic • Biaxial (+) Mohs ~6–6.5 • SG ~3.3–3.5 Epidote 🌿 — Pistachio‑Green Glow from the Heart of Metamorphic Rocks Vivid green, strongly pleochroic, and a...
Howlite
Howlite • calcium borate mineral Formula: Ca2B5SiO9(OH)5 • System: Monoclinic Hardness: ~3.5 • SG: ~2.53 • Luster: dull to sub‑vitreous (satin when polished) Look: chalk‑white to grey‑white with spiderweb black/grey...
Howlite
Howlite • calcium borate mineral Formula: Ca2B5SiO9(OH)5 • System: Monoclinic Hardness: ~3.5 • SG: ~2.53 • Luster: dull to sub‑vitreous (satin when polished) Look: chalk‑white to grey‑white with spiderweb black/grey...
Hypersthene
Hypersthene • Orthopyroxene Series (varietal name) Formula: (Mg,Fe)SiO3 • Orthorhombic Mohs ~5.5–6 • SG ~3.3–3.5 Cleavage: 2 directions ≈90° (prismatic) Optics: Biaxial (+); Pleochroic browns/greens Phenomenon: Bronze/silvery “schiller” Hypersthene —...
Hypersthene
Hypersthene • Orthopyroxene Series (varietal name) Formula: (Mg,Fe)SiO3 • Orthorhombic Mohs ~5.5–6 • SG ~3.3–3.5 Cleavage: 2 directions ≈90° (prismatic) Optics: Biaxial (+); Pleochroic browns/greens Phenomenon: Bronze/silvery “schiller” Hypersthene —...
Iolite
Iolite • Gem‑quality Cordierite Formula: (Mg,Fe)2Al4Si5O18 • Cyclosilicate Crystal System: Orthorhombic • Biaxial (–) Mohs ~7–7.5 • SG ~2.58–2.66 RI ~1.542–1.578 • Birefringence ~0.008–0.012 Trait: Intense trichroism (“water sapphire”) Iolite...
Iolite
Iolite • Gem‑quality Cordierite Formula: (Mg,Fe)2Al4Si5O18 • Cyclosilicate Crystal System: Orthorhombic • Biaxial (–) Mohs ~7–7.5 • SG ~2.58–2.66 RI ~1.542–1.578 • Birefringence ~0.008–0.012 Trait: Intense trichroism (“water sapphire”) Iolite...
Dumortierite
Dumortierite • complex aluminum borosilicate — approx. formula Al₇BO₃(SiO₄)₃O₃ Crystal system: Orthorhombic • Habit: fibrous, radial, prismatic; massive/granular Mohs: ~7–8.5 • SG: ~3.27–3.39 • Luster: vitreous to silky Pleochroism: distinct...
Dumortierite
Dumortierite • complex aluminum borosilicate — approx. formula Al₇BO₃(SiO₄)₃O₃ Crystal system: Orthorhombic • Habit: fibrous, radial, prismatic; massive/granular Mohs: ~7–8.5 • SG: ~3.27–3.39 • Luster: vitreous to silky Pleochroism: distinct...
Heliotrope
Heliotrope (Bloodstone) • variety of chalcedony — microcrystalline SiO₂ Look: deep green base with red iron‑oxide spots; “plasma” = green with few/no red marks Mohs: ~6.5–7 • SG: ~2.58–2.64 •...
Heliotrope
Heliotrope (Bloodstone) • variety of chalcedony — microcrystalline SiO₂ Look: deep green base with red iron‑oxide spots; “plasma” = green with few/no red marks Mohs: ~6.5–7 • SG: ~2.58–2.64 •...