Mineral Based Alloy (Anthropogenic)

Granitic Gravel Piece

Granite (Felsic Plutonic Rock / SiO2 with Al2O3, K2O, Na2O)

Rainbow Hematite (Man-made/Treated)

Tumbled Hematite with Titanium/Anodized coating (Iron(III) oxide, Fe2O3)

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Fuchsite

K(Al,Cr)2(AlSi3O10)(OH)2 (Chromium-rich Muscovite)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Bismuth Crystal

Bismuth (Bi)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Sandstone (Quartzose Sandstone)

Arenite (SiO2 primarily)

Sandstone (Weathered Pebble)

Arenite (composed primarily of SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (composed primarily of SiO2)

Granite

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

Conglomerate

Conglomerate (a clastic sedimentary rock)

Biotite Schist

Biotite Mica Schist [K(Mg,Fe)3AlSi3O10(OH,F)2]

Granite

Granite (Felsic Plutonic Rock)

Amygdaloidal Rhyolite

Rhyolite (felsic volcanic rock) with amygdules

Nuummite

Nuummite (Orthorhombic amphiboles: Anthophyllite and Gedrite)

Pink Granite

Phaneritic Felsic Igneous Plutonic Rock

Basalt with Quartz/Zeolite Inclusions

Porphyritic Basalt (SiO2 with Aluminosilicates)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Vesicular Basalt (Amygdaloidal)

Vesicular Basalt (Fe-Mg rich extrusive volcanic rock)

Epidote in Basalt

Epidotized Basalt (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH) in Mafic Igneous Host)

Basalt

Basalt (composition of plagioclase, pyroxene, and olivine)

Tree Agate

Silicon Dioxide with Chlorite inclusions (SiO2)

Fuchsite (Green Muscovite in Quartz)

K(Al,Cr)2(AlSi3O10)(OH)2 - Chromium-rich Muscovite

Lepidolite on Pegmatite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Weathered Quartzite or Chert Pebble

Silicon Dioxide (SiO2)

Chert Pebble with Quartz Veining

Microcrystalline Quartz (SiO2)

Boulder Opal

Precious Opal in Ironstone (Amorphous Hydrated Silica, SiO2·nH2O)

Grey Chalcedony (Tumbled)

Chalcedony (SiO2)

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Heat-Treated Amethyst (Commercial Citrine)

Silicon Dioxide (SiO2) - Macro-crystalline Quartz

Mica (Biotite and Muscovite) in Matrix

Potassium aluminum silicate with iron/magnesium (KAl2(AlSi3O10)(F,OH)2 / K(Mg,Fe)3AlSi3O10(F,OH)2)

Granodiorite (Water-worn Pebble)

Granodiorite

Chlorite (Small Flakes/Sand)

Chlorite Group (Magnesium Iron Aluminum Silicate Hydroxide - (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6)

Basalt with Limonite stains

Extrusive mafic igneous rock; Limonite (FeO(OH)·nH2O)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Basalt with Epidote Veining

Basalt (Mafic Extrusive Rock) with Ca2(Al,Fe)3(SiO4)3(OH)

Diorite

Intermediate plutonic igneous rock

Orbicular Jasper (Ocean Jasper variant)

Silicon Dioxide (SiO2) with iron oxide inclusions

Greenschist

Greenschist (Chlorite Schist)