Mineral Like Biological Tissue

Emerald in Matrix

Beryl (Be3Al2Si6O18) with trace amounts of Chromium/Vanadium

Amethyst (Tumbled Chips)

Amethyst (Silicon Dioxide with Iron impurities, SiO2)

Turquoise

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

Obsidian

Volcanic Glass (SiO2 - Silicon Dioxide with impurities)

Native Copper with Malachite and Chrysocolla

Native Copper (Cu) with Malachite [Cu2CO3(OH)2] and Chrysocolla [(Cu,Al)2H2Si2O5(OH)4·nH2O]

Moss Agate

Silicon Dioxide (SiO2) with mineral inclusions

Ocean Jasper

Orbicular Jasper (Silicon Dioxide with impurities), SiO2

Quartz Geode (partially formed)

Silicon Dioxide (SiO2)

Limonite (Yellow Ochre)

Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)

Sandstone (Red)

Arenite (primarily Quartz, SiO2, with Iron Oxide cement)

Chalcedony (specifically Agate or Carnelian variety)

Cryptocrystalline Silica (SiO2)

Fulgurite

Fulgurite (Lechatelierite-rich variety)

Satin Spar Selenite

Gypsum (CaSO4·2H2O)

Heat-Treated Amethyst (Commercial Citrine)

Silicon Dioxide (SiO2) - Macro-crystalline Quartz

Dyed Howlite

Borosilicate hydroxide (Ca2B5SiO9(OH)5)

Milky Quartz

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Prehnite

Prehnite - Ca2Al(AlSi3O10)(OH)2

Pyrite

Iron Disulfide (FeS2)

Moss Agate

Silicon Dioxide with inclusions (SiO2 + Fe/Mn/Mg)

Glauconite (Glauconitic Sandstone)

Glauconite [(K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2]

Sandstone (likely Iron-rich or Arkosic)

Arenite (SiO2 with FeO(OH) or Fe2O3 staining)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Agate Geode

Chalcedony (cryptocrystalline SiO2)

Garnet (likely Pyrope or Almandine)

Garnet Group (complex nesosilicate minerals, e.g., Pyrope Mg3Al2(SiO4)3, Almandine Fe3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3, Grossular Ca3Al2(SiO4)3, Andradite Ca3Fe2(SiO4)3, Uvarovite Ca3Cr2(SiO4)3). The vivid red color in the image strongly suggests Pyrope or Almandine.

Obsidian

Obsidian (Volcanic Glass) SiO2 (70% or more)

Amethyst

Silicon Dioxide (SiO2) with trivalent iron (Fe3+) impurities

Pyrite (Fool's Gold) in Matrix

Iron Sulfide (FeS2)

Red Cubic Zirconia (Simulated Garnet)

Zirconium Dioxide (ZrO2)

Granite Gneiss

Gneiss (derived from granitic protolith)

Limonite Pseudomorph after Pyrite

Limonite (FeO(OH)·nH2O) replacing Pyrite (FeS2)

Chrysocolla in Quartz (Gem Silica)

Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla) / SiO2 (Quartz)

Dendritic Agate (specifically Orange/Tumbled)

Silicon Dioxide (SiO2) with Oxide Inclusions

Citrine

Silicon Dioxide (SiO2)

Granodiorite

Granodiorite (intermediate plutonic rock)

Red Jasper

Jasper (Silicate mineral - SiO2)

Quartzite

Quartzite (Primary mineral: SiO2)

Garnet

Garnet Group (Silicate Minerals), formula varies e.g., Almandine Fe3Al2(SiO4)3

Rutilated Quartz

SiO2 with TiO2 inclusions

Red Hematite (Banded Iron Formation)

Hematite (Fe2O3)

Dyed Quartz Geode

Silicon Dioxide (SiO2) with artificial pigment

Basalt

Mafic Igneous Rock