Sedimentary Or Igneous (Host Environment)

Rock Crystal Quartz

Quartz (SiO₂)

Turquoise in Matrix

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

Sandstone Concretion

Sedimentary Concretion (Quartz sand bound by mineral cement)

Hag Stone

Naturally holed stone (typically sedimentary rock such as flint, limestone, or sandstone)

Banded River Cobble with Mafic Dike

Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion

Veined Limestone (or Quartz-Veined Slate/Shale)

Metamorphosed Sedimentary Rock with Calcite/Quartz Veins

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Quartz (Smoky/Milky variety)

Silicon Dioxide (SiO2)

Chert (Varietal Agate/Jasper)

Silicon Dioxide (SiO2)

Quartz with Chalcopyrite (or Pyrite)

Silicon Dioxide (SiO2) with Copper Iron Sulfide (CuFeS2)

Weathered iron-rich stone, likely basalt or ironstone

Indeterminate; possibly vesicular basalt (plagioclase–pyroxene) or ferruginous sandstone/ironstone

Weathered sandstone

Quartz-rich clastic sandstone, likely iron-oxide-stained

Quartz Pebble

Silicon Dioxide (SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Pebble of weathered basalt or andesite

Fine- to medium-grained mafic volcanic rock; commonly plagioclase ± pyroxene, olivine, and iron oxides

Polished jasper pebble (possibly orbicular jasper)

Microcrystalline quartz (SiO₂), likely jasper; exact variety cannot be confirmed visually

Quartz Druze on Matrix (Geode Fragment)

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Rounded metamorphic pebble, likely mica schist or gneiss

Mica schist/gneiss; commonly quartz, feldspar, and biotite or muscovite mica

Quartz Pebble

Silicon Dioxide (SiO2)

Weathered metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification is uncertain from the photograph

Native Copper in Basalt

Cuprum (with Host Basalt)

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Gneiss (specifically Granitic Gneiss)

Gneiss

Granite Gneiss River Rock

Gneiss

Glauconitic Sandstone

Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)

Conglomeratic breccia (possibly polymictic volcanic breccia)

Polymictic breccia; clasts in a fine-grained volcanic or sedimentary matrix

Quartz

Silicon dioxide (SiO2)

Likely foliated metamorphic rock (quartz-mica schist or gneiss)

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and tests

Limestone ( weathered ) / Chert Nodular Rock

Sedimentary rock (primarily Calcium Carbonate, CaCO3, with Microcrystalline Quartz, SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Quartz Druze

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Pink Opal

Amorphous Hydrous Silica (SiO2·nH2O)

River Pebble (Gneiss / Granitic Schist)

Metamorphic Rock (Quartz-Feldspar-Mica assembly)

Metallic sulfide mineral specimen, likely pyrite

Pyrite (FeS₂), possibly a pyrite-rich sulfide aggregate

Limestone (Brecciated/Recrystallized)

Calcium Carbonate (CaCO3)

Quartz Heart or Arrowhead Shape

Silicon Dioxide (SiO2)

Likely raw mica-bearing metamorphic rock or mineral fragment

Tentatively biotite schist; visually similar dark mica-rich material

Quartz Pebble

Silicon Dioxide (SiO2)