Mineral Like Biological Tissue

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Quartz (Microcrystalline/Chert)

Silicon Dioxide (SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Honey Calcite

Calcium Carbonate (CaCO3)

Quartz (Druzy or Crystalline variety)

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Folded Schist / Gneiss (Metamorphic Rock)

Regional Metaphoric Folded Outcrop (predominantly Schist/Gneiss)

Pyrite

Iron Disulfide (FeS2)

Diorite

Phaneritic intermediate plutonic rock

Granite

Granite (a phaneritic intrusive igneous rock consisting mainly of quartz, alkali feldspar, and plagioclase)

Pegmatite (Granite Pegmatite)

Intrusive Igneous Rock (Granite Pegmatite)

Coarse-grained Quartz with Feldspar inclusions

Crystalline Quartz (SiO2) with Orthoclase/Plagioclase Feldspar inclusions

Granite

Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)

Granite

Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Fire Opal (Common/Precious in Matrix)

Hydrated Silica (SiO2·nH2O)

Petrified Wood

Silicified Wood (SiO2)

Banded Agate (specifically Chalcedony nodule)

Agate (Silicon Dioxide, SiO2)

Banded Agate (Carnelian type)

Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Peacock Ore

Bornite (Cu5FeS4)

Silicon Carbide (Carborundum)

Silicon Carbide (SiC)

Moqui Marble

Ironstone Concretion (Goethite/Hematite shell with Sandstone core)

Amethyst (in jewelry)

Silicon Dioxide (SiO2) with iron impurities

Common Opal

Hydrated silica (SiO2 " nH2O)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) in matrix

Desert Rose

Gypsum (Calcium Sulfate Dihydrate, CaSO4·2H2O) or Barite (Barium Sulfate, BaSO4)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Quartz Vein in Sedimentary Matrix

Silicon Dioxide (SiO2) with host rock

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide with Iron Oxide (SiO2 with traces of Fe2O3/FeO(OH))

Milky Quartz

Silicon Dioxide (SiO2)

Specular Hematite (Iron Ore)

Iron(III) oxide (Fe2O3)

Limonite-pseudomorph after Pyrite (Prophecy Stone)

Goethite and Limonite secondary minerals (FeO(OH)·nH2O) replacing Pyrite (FeS2)

Dark-colored Igneous Rock (likely Basalt or Diabase)

Basalt (extrusive igneous) or Diabase (intrusive igneous)

Shale (with minor calcite veining)

Clastic sedimentary rock (primarily clay minerals and quartz)

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Malachite

Copper Carbonate Hydroxide [Cu2CO3(OH)2]

Turquoise (set in silver jewelry)

Turquoise - CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminum phosphate)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Chert (and its variety Flint)

Silicon Dioxide (SiO2) - Microcrystalline or cryptocrystalline Quartz