Quartz
Silicon Dioxide (SiO₂)
Category
Browse the purple specimen is a mineral (amethyst); the white specimen is a sedimentary rock (limestone or marble). specimens identified by the Rock Identifier community.
Quartz
Silicon Dioxide (SiO₂)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Amethyst
Amethyst (Silicon Dioxide with Iron impurities), SiO2
Marble
Metamorphosed Limestone (principally CaCO3)
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
Amethyst Geode
Silicon dioxide (SiO2) with iron impurities
Quartz (likely Rose Quartz or Milky Quartz based on color)
Quartz (SiO2 - Silicon Dioxide)
Amethyst
Amethyst (Purple Quartz); formula: SiO2 (Silicon Dioxide)
Amethyst
Silicon dioxide with iron impurities (SiO2:Fe3+)
Lapis Lazuli (Tumbled Specimen)
Lapis Lazuli (Aggregate rock containing Lazurite: (Na,Ca)8(AlSiO4)6(SO4,S,Cl)2)
Banded Onyx (Calcite Marble)
Calcite (CaCO3) - Trap-rock or Cave Onyx
Geode (unopened)
SiO2 - Chert-shelled concretion (mostly Quartz)
Amethyst
Silicon dioxide with iron impurities (SiO2)
Heat-Treated Citrine (Amethyst)
Silicon Dioxide (SiO2) with iron impurities
Amethyst (Chevron or Banded Amethyst)
Silicon Dioxide (SiO2 with iron impurities)
Orange Calcite
Calcium Carbonate (CaCO3)
Marble
Recrystallized Calcite (CaCO3)
Geode with Quartz/Chalcedony
Silicon Dioxide (SiO2)
Amethyst
SiO2 (Silicon Dioxide with iron impurities)
Charoite
Charoite (Hydrated potassium sodium calcium barium strontium silicate hydroxyfluoride)
Amethyst
Quartz (Silicon Dioxide with Iron impurities), SiO2
Amethyst
SiO2 (Silicon Dioxide with Iron impurities)
Orange Calcite
Calcium Carbonate (CaCO3)
Calcite (likely a tumbled specimen)
Calcite (CaCO 3 )
Quartz (pebble)
Quartz (SiO₂)
Quartzite
Quartzite (SiO2)
Mixed Quartz and River Pebbles (Stone Collection)
Mixed assortment containing mainly Silicon Dioxide (SiO2)
Calcite
Calcium Carbonate (CaCO3)
Fluorite, Turquoise, and Calcite set
Calcium Fluoride (CaF2), Hydrous Phosphate of Copper and Aluminum (CuAl6(PO4)4(OH)8·4H2O), Calcium Carbonate (CaCO3)
Blue Calcite
Calcite (Calcium Carbonate, CaCO3)
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
Chevron Amethyst
Silicon Dioxide (SiO2) with iron impurities
Quartz Vein in Sedimentary Rock
Silicon Dioxide (SiO2) with host Chert or Limestone
Marble
Recrystallized Calcite (CaCO3)
Amethyst
Crystalline Silicon Dioxide with Iron impurities (SiO2)
Fluorite with Quartz coating
Calcium Fluoride (CaF2) with Silicon Dioxide (SiO2)
Quartz Geode Fragment
Silicon Dioxide (SiO2)
Quartz (on matrix)
Quartz (Silicon Dioxide, SiO₂)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Amethyst
Crystalline Quartz (SiO2 with iron impurities)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Quartz
Quartz (SiO2 - Silicon Dioxide)