Mineral (Tectosilicate)

Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Red Sandstone

Clastic sedimentary rock (primarily SiO2 with Fe2O3 iron oxide staining)

Turquoise

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

Sandstone

Arenite (composed primarily of SiO2)

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Shale with Iron Oxide Staining

Fissile Mudstone (primarily clay minerals and quartz)

Basalt Porphyry

Porphyritic Basalt

Chert (Jasper/Flint variant)

Microcrystalline Quartz (SiO2)

Larimar

Pectolite (a blue variety of Pectolite)

Turquoise

Turquoise (Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O)

Quartz with Pyrite and Iron Staining

Silicon Dioxide (SiO2) with Iron Disulfide (FeS2) inclusions

Arfvedsonite (often mistakenly sold as Astrophyllite)

Arfvedsonite [Na3(Fe2+)4Fe3+Si8O22(OH)2]

Pegmatite

Coarse-grained Igneous Rock (Granitic Pegmatite)

Granite Pebble

Granite (Phaneritic intrusive igneous rock comprising Quartz, Feldspar, and Mica)

Ocean Jasper (Orbicular Jasper)

Silicon Dioxide (SiO2) with iron and other mineral inclusions

Sandstone

Arenite (SiO2 principal)

Granite (Fine-grained)

Phaneritic Felsic Igneous Rock

Geode (Unopened)

Silicon Dioxide (SiO2) in sedimentary host rock

Limestone Gravel

Calcium Carbonate (CaCO3)

Blue Quartz with Graphite/Tourmaline Inclusions

Silicon Dioxide (SiO2) with Carbon (C) or Schorl elements

Quartz (Raw and Water-worn)

Silicon Dioxide (SiO2)

Rose Quartz

Silicon Dioxide (SiO2)

Sunstone

Oligoclase (Feldspar variety)

Amethyst

Silicon dioxide with iron impurities (SiO2 + Fe3+)

Orbicular Jasper (Ocean Jasper)

Silicon Dioxide (SiO2) with various inclusions

Amazonite

Microcline (variety Amazonite), K(AlSi3O8)

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Alexandrite

Chrysoberyl (BeAl2O4 with Chromium impurities)

Chalcopyrite

Chalcopyrite (CuFeS2)

Gold Nugget (Placer Gold)

Native Gold (Au)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Herkimer Diamond

Double-terminated Quartz (Silicon Dioxide, SiO2)

Limonite Pseudomorph after Pyrite

Limonite (Hydrous iron oxides e.g., FeO(OH)·nH2O) pseudomorphing Pyrite (FeS2)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Amethyst

Silicon Dioxide (SiO2) with trace Iron (Fe3+)

Chalcedony (Botryoidal or Chalcedony Rose)

Silicon dioxide (SiO2)

Ruby in Quartz with Tourmaline

Corundum (Al2O3) in Silicon Dioxide (SiO2) with Schorl

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8)

Arfvedsonite with Garnet

Na3(Fe2+,Mg)4Fe3+Si8O22(OH)2

Ocean Jasper

Orbicular Jasper (Silicon Dioxide, SiO2)

Ocean Jasper

Orbicular Jasper (Silicon Dioxide, SiO2)