Synthetic Material (Not A Rock Or Mineral)

Banded Sandstone

Arenite (composed primarily of Quartz: SiO2)

Ironstone Concretion

Siderite / Hematite-bearing Sedimentary Rock

Tufa

Calcareous Tufa (Calcium carbonate, CaCO3)

Sandstone

Arenite

Granite Pegmatite with Muscovite Mica

Granite Pegmatite (Silicon Dioxide and complex silicates)

Sandstone

Arenite (SiO2 based clastic rock)

Chert Nodules in Limestone

Microcrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)

Iron-rich quartzite or limonite-bearing rock

Quartzite (SiO₂) with iron oxides/hydroxides, chiefly hematite and goethite

Granite Cobble (River Stone)

Felsic intrusive igneous rock (composition: Quartz, Feldspar, Mica)

Fuchsite

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

Green Fluorite in Host Rock

Fluorite (Calcium Fluoride, CaF2)

Petrified Wood

Silicified Wood (SiO2)

Black Marble

Recrystallized Carbonate Rock (CaCO3)

Red-and-cream jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Granite

Granite (Phaneritic intrusive igneous rock)

Granite Pebble

Granite (Plutonic Igneous Rock)

River Cobble (Basaltic/Andesitic)

Mafic Igneous Porphyritic Rock

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily Quartz - SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Arenite / Sandstone

Quartz sandstone (SiO2 rich clastic sedimentary rock)

Slag (Industrial Glass/Glassy Rock)

Anthropogenic Vitreous Material

Tumbled brown agate or jasper

Microcrystalline quartz, SiO₂ (likely chalcedony/agate with iron oxides)

Polished agate/jasper pebble

Microcrystalline quartz (chalcedony), SiO₂, with likely iron-oxide and clay inclusions

Quartz (Gravel fragment)

Quartz (Silicon Dioxide, SiO2)

Weathered fossiliferous limestone fragment, possibly fossil coral or shell material

Indeterminate carbonate fossil in calcitic limestone; likely composed mainly of calcite (CaCO₃), but species identification is not possible from this image alone

Diorite

Diorite (an intrusive igneous rock)

Green serpentine

Serpentine-group minerals, chiefly lizardite and antigorite; approximate formula Mg₃Si₂O₅(OH)₄

Weathered granitic rock

Granite or granodiorite; mainly quartz, feldspar, and mica/amphibole

Weathered sandstone or arkosic sandstone

Clastic sandstone, likely quartz–feldspar-rich (arkose)

Basalt with Quartz/Calcite Vein

Aphanitic Mafic Volcanic Rock with Quartz (SiO2) or Calcite (CaCO3) Vein

Sodalite-bearing rock, likely sodalite-rich syenite or sodalite in feldspathic matrix

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, with probable feldspar and accessory minerals

Diorite (River Pebble)

Intermediate plutonic igneous rock

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Weathered granite or granitic gneiss

Granite: quartz, feldspar, and mica; possibly weakly foliated gneiss

Petrified Wood

Silicified Wood (SiO2)

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Porphyritic granite or granodiorite

Coarse-grained plutonic rock composed mainly of quartz (SiO₂), feldspar, and mica/amphibole

Gabbro

Gabbro

Olivine in Basalt (Peridot)

Magnesium Iron Silicate (Mg, Fe)2SiO4 in Vesicular Basalt

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)