Cordierite in Matrix (Iolite)
Magnesium iron aluminium cyclosilicate (Mg,Fe)2Al4Si5O18
metamorphic
Category
Not A Geological Specimen
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Milky Quartz
Silicon Dioxide (SiO2)
mineral
Weathered Sandstone with Algae Growth
Arenite
sedimentary
Granitic Pegmatite with Schorl Tourmaline
Granitic Pegmatite (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4)
igneous
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
Mineral (Variety of Chalcedony)
Quartz Pebble (Geode-like)
Silicon Dioxide (SiO2)
Mineral
Chalcedony (Agate)
Silicon Dioxide (SiO2)
mineral
Agate
Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony
Mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Basalt with Pahoehoe flow texture
Vesicular Basalt (Aphanitic Mafic Igneous Rock)
igneous
Green Calcite
Calcium Carbonate (CaCO3)
mineral
Nephrite (a form of Jade)
Nephrite (a variety of the mineral actinolite, Ca2(Mg,Fe)5Si8O22(OH)2)
Mineral
Orange Calcite
Calcite (Calcium Carbonate - CaCO3)
mineral
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
mineral
Sandstone
Arenite (SiO2 based with quartz grains)
sedimentary
River Pebble (Greywacke or Siltstone)
Clastic Sedimentary Rock
sedimentary
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
mineral
Quartz Geode
Silicon Dioxide (SiO2) in a Secondary Formation
sedimentary
Quartz (Iron-stained or Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Glaucophane Schist (Blueschist)
Blueschist facies metamorphic rock
metamorphic
Pyrite
Iron Disulfide (FeS2)
mineral
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
mineral
Chert (Arrowhead variety)
Chert (SiO2)
sedimentary
Sandstone (Quartzite Pebble)
Arenite / Metamorphosed Sandstone (SiO2)
sedimentary
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Satin Spar (often marketed as Selenite)
Fibrous Gypsum (CaSO4·2H2O)
mineral
Milky Quartz (Water-worn Pebble)
Quartz (Silicon Dioxide, SiO2)
mineral
Chert (Iron-stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Apatite
Apatite group mineral (e.g., Fluorapatite - Ca5(PO4)3F, Chlorapatite - Ca5(PO4)3Cl, Hydroxylapatite - Ca5(PO4)3(OH))
mineral
Iron-stained Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
mineral
Slate with Red Sandstone Landscaping Rock
Foliated Pelitic Metamorphic Rock (Slate) and Ferruginous Sandstone
metamorphic and sedimentary
Pyrite
Iron Sulfide (FeS2)
mineral
Quartz (Specifically Clear to Smoky Quartz point)
Silicon Dioxide (SiO2)
mineral
White Quartz Star-cut crystal
Silicon Dioxide (SiO2)
mineral
Yellow Chert (Gold-toned Jasper)
Silicon Dioxide (SiO2)
sedimentary
Granite Cobble
Granite (Phaneritic igneous rock composed of Quartz, Feldspar, and Mica)
igneous
Chert (Jasper)
Cryptocrystalline Quartz (SiO2)
sedimentary
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Pyrite
Iron Disulfide (FeS2)
mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral