Sandstone
Arenite (primary component SiO2)
sedimentary
Category
Mineral Based Alloy (Anthropogenic)
Browse mineral based alloy (anthropogenic) specimens identified by the Rock Identifier community.
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Diamond
Diamond (a metastable allotrope of carbon, C)
Mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Greenschist (Chlorite Schist)
Greenschist (Metamorphic rock dominated by chlorite, actinolite, and epidote)
metamorphic
Mica Schist
Mica Schist (primarily Muscovite or Biotite sheet silicates)
metamorphic
Pink Granite
Phaneritic Plutonic Rock (Felsic)
igneous
Riverstone (Quartzite/Granite Cobble)
Silicon Dioxide (SiO2) based Quartzite or Silicate-rich Granite
metamorphic or igneous
Anthracite Coal
Anthracite (Carbon-based organic sedimentary rock transitioned to metamorphic)
metamorphic
Mystic Topaz
Aluminum silicate fluoride hydroxide with titanium coating (Al2SiO4(F,OH)2)
mineral
Amygdaloidal Basalt
Amygdaloidal Basalt
Igneous
Granite
Granite (Felsic Plutonic Rock)
igneous
Granodiorite
Granodiorite
igneous
Mystic Topaz
Aluminum Silicate Fluoride Hydroxide (Al2SiO4(F,OH)2) with metallic film coating
mineral
Chrysocolla in Jasper (Chryso-Jasper)
Cu2-xAlx(H2-xSi2O5)(OH)4·n H2O (Chrysocolla) + SiO2 (Jasper)
mineral
Chalcedony (Common Agate pebble)
Silicon Dioxide (SiO2)
mineral
Gneiss (with Quartz-Feldspar vein)
Gneiss (high-grade metamorphic rock) containing Quartz (SiO2) and Feldspar (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8)
metamorphic
Buffalo Nickel (Indian Head Nickel)
Cupronickel (75% Copper, 25% Nickel)
mineral (processed alloy)
Fossilized Shark Tooth
Eocene Lamniformes (Mackerel Shark clade)
fossil
Snowflake Obsidian
Volcanic Glass with Cristobalite Inclusions
igneous
Limonite-stained Quartz
Silicon Dioxide (SiO2) with Iron Oxide/Hydroxide (FeO(OH)·nH2O) staining
mineral
Pink Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
mineral
Quartz with Muscovite Mica
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate Hydroxide (KAl2(AlSi3O10)(OH)2)
mineral
Biotite (Mica)
K(Mg,Fe)3AlSi3O10(OH,F)2
mineral
Gravel or Crushed Stone
Fragmented Aggregate Stone
sedimentary or igneous fragment
Sandstone
Arenite (SiO2 principal)
sedimentary
Amygdaloidal Basalt with Epidote/Chlorite
Basalt (containing (Ca2(Al2Fe3+)(SiO4)(Si2O7)O(OH)))
igneous
Silicon Carbide (Carborundum)
Moissanite (SiC), though mostly synthetic
mineral
Heat-Treated Citrine (Amethyst)
Silicon Dioxide (SiO2) with iron impurities
mineral
Druzy Quartz on Chert/Chalcedony
Silicon Dioxide (SiO2)
mineral
Schist
Mica Schist
metamorphic
Potassium-Rich Silicate Clay (inferred from biological context)
Phyllosilicate group (likely Illite or Smectite within surrounding soil substrate)
mineral
Amazonite (likely mixed with other feldspars/minerals)
Amazonite is a variety of Microcline, which is a tectosilicate mineral, formula KAISi3O8. The mixed beads could include other feldspars or quartz.
Mineral
K2 Jasper (K2 Granite)
Azurite in Granite (Al2Cu3(CO3)2(OH)2 in NaAlSi3O8)
igneous
Vesicular Basalt (Amygdaloidal)
Amygdaloidal Basalt
igneous
K2 Jasper (K2 Granite)
Azurite in Granite (Biotite Granite containing Azurite)
igneous
Aura Quartz (Titanium-coated Quartz)
Silicon Dioxide (SiO2) with metallic vapor coating
mineral
Epidote
Epidote Group (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
metamorphic
Vesicular Basalt
Basalt with vesicular texture
igneous
Mixed Gemstone Bracelet
Mixed natural minerals and rocks (e.g., Rhodonite, Malachite, Sodalite, Rose Quartz, Black Tourmaline, Quartz/Chalcedony variants)
Mineral/Rock assemblage
Ferrochrome Slag
Anthropogenic silicate/oxide glass (Complex silicate matrix with Cr-Fe-Si inclusions)
Industrial byproduct (often confused with igneous rocks or meteorites)
Covellite
Covellite (CuS)
mineral
Asphalt Concrete (Bituminous Pavement)
Aggregates in Bitumen Matrix
Technogenic / Anthropogenic Pavement Material