Kristalopedia
Iolites
Iolite • gemstone-quality cordierite Formula: (Mg,Fe)2To the4Yes5O18 • cyclosilicate Crystal system: orthorhombic • biaxial (–) Mohs ~7–7.5 • SG ~2.58–2.66 RI ~1.542–1.578 • birefringence ~0.008–0.012 Feature: intense trichroism ("water sapphire")...
Iolites
Iolite • gemstone-quality cordierite Formula: (Mg,Fe)2To the4Yes5O18 • cyclosilicate Crystal system: orthorhombic • biaxial (–) Mohs ~7–7.5 • SG ~2.58–2.66 RI ~1.542–1.578 • birefringence ~0.008–0.012 Feature: intense trichroism ("water sapphire")...
Hovlitas
Howlite • calcium borate mineral Formula: Ca2B5SiO9(OH)5 • System: monoclinic Hardness: ~3.5 • SG: ~2.53 • Luster: from matte to semi-glassy (polished – satin) Appearance: chalk white to grayish white...
Hovlitas
Howlite • calcium borate mineral Formula: Ca2B5SiO9(OH)5 • System: monoclinic Hardness: ~3.5 • SG: ~2.53 • Luster: from matte to semi-glassy (polished – satin) Appearance: chalk white to grayish white...
Iceland spar
Iceland spar • optical quality calcite — CaCO₃ Crystal system: trigonal (rhombohedral) • Variety: transparent rhombohedra Mohs scale: 3 • SG: ~2.71 • Cleavage: perfect in 3 directions (rhombohedral) Optics:...
Iceland spar
Iceland spar • optical quality calcite — CaCO₃ Crystal system: trigonal (rhombohedral) • Variety: transparent rhombohedra Mohs scale: 3 • SG: ~2.71 • Cleavage: perfect in 3 directions (rhombohedral) Optics:...
Krinoidas
Crinoid fossil • “Sea lily” Class Crinoidea • Phylum Echinodermata (echinoderms) Age: Ordovician–present (peak – Mississippian) Typical composition: calcite • sometimes silicified Crinoid fossil 🌊 — Ocean ferns carved in...
Krinoidas
Crinoid fossil • “Sea lily” Class Crinoidea • Phylum Echinodermata (echinoderms) Age: Ordovician–present (peak – Mississippian) Typical composition: calcite • sometimes silicified Crinoid fossil 🌊 — Ocean ferns carved in...
Deimantas
Diamond • C (carbon) Isometric (cubic) Mohs 10 • highest hardness RI 2.417 • Dispersion 0.044 Diamond 💎 — The science of fire, sparkle, and brilliance Harder than nails, glass,...
Deimantas
Diamond • C (carbon) Isometric (cubic) Mohs 10 • highest hardness RI 2.417 • Dispersion 0.044 Diamond 💎 — The science of fire, sparkle, and brilliance Harder than nails, glass,...
Diumorteritas
Dumortierite • complex aluminum borosilicate — approximate formula Al₇BO₃(SiO₄)₃O₃ Crystal system: orthorhombic • Habit: fibrous, radial, prismatic; massive / granular Mohs: ~7–8.5 • SG: ~3.27–3.39 • Luster: vitreous → silky...
Diumorteritas
Dumortierite • complex aluminum borosilicate — approximate formula Al₇BO₃(SiO₄)₃O₃ Crystal system: orthorhombic • Habit: fibrous, radial, prismatic; massive / granular Mohs: ~7–8.5 • SG: ~3.27–3.39 • Luster: vitreous → silky...