Mineral In A Matrix (Likely Quartz Or Feldspar)

Fossil gastropod in granite-like stone

Gastropoda indet.; enclosing rock likely polished granite or gneiss

Porphyritic Rhyolite

Rhyolite (Porphyritic texture)

Blue-gray metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica assemblage; exact identification requires testing

Quartz vein in weathered host rock

Milky quartz (SiO₂), likely in a granitic or metamorphic matrix

Conglomeratic volcanic breccia

Lithic volcanic breccia, likely andesitic or basaltic

Rhyolite

Rhyolite, felsic extrusive igneous rock

Quartz-rich conglomeratic rock (likely granitic breccia or conglomerate)

Uncertain; quartz–feldspar rock in a fine-grained matrix, possibly weathered granite or polymictic conglomerate

Pyrite in Matrix (likely Quartz or Coal)

Iron Sulfide (FeS2)

Quartz-rich pegmatite (likely feldspar–quartz rock)

Granitic pegmatite; chiefly quartz (SiO₂) and feldspar, with possible mica/iron-oxide staining

Mica-rich granite or granitic pegmatite

Biotite granite; primarily quartz, feldspar, and biotite mica

Unidentified weathered rock fragment

Likely granitic or feldspathic rock; exact identification requires clearer imaging and testing

Basalt (with Plagioclase Phenocrysts)

Porphyritic Basalt

Garnet-bearing granite or pegmatitic granitic rock

Coarse-grained granitoid, likely granite or pegmatite, composed mainly of quartz and feldspar with almandine/spessartine garnet and dark biotite or amphibole

Likely rose quartz-bearing pegmatite

Quartz (SiO₂), probably with feldspar and iron-oxide staining

Uncertain polymict breccia or altered volcanic rock

Likely hydrothermally altered volcanic breccia; exact mineral identification requires testing

Unidentified weathered rock, possibly quartz-bearing granite or rhyolite

Indeterminate; likely quartz–feldspar-rich silicate rock

Glacial Granite with Epidote

Granite featuring Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Green glassy mineral specimen, likely rough emerald or green fluorite

Tentatively beryl (Be₃Al₂Si₆O₁₈), emerald variety; synthetic/man-made glass cannot be excluded from the photograph

Likely weathered granite or pegmatitic rock

Granite/pegmatite; primarily quartz (SiO₂), feldspar, and mica

Quartz-rich pegmatite fragment

Milky quartz with feldspar and mica; primarily SiO₂, with K-feldspar/plagioclase and muscovite

Weathered quartz-rich rock fragment

Likely quartz-bearing sandstone or granitic rock; exact identification is uncertain from the image

Tourmaline-bearing pegmatite

Quartz–feldspar pegmatite with black schorl tourmaline (NaFe3Al6(BO3)3Si6O18(OH)4)

Blue-green tourmaline (likely indicolite)

Elbaite tourmaline, Na(Li1.5Al1.5)Al6(BO3)3Si6O18(OH)4

Granite Pebble

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

Tumbled lepidolite-rich pegmatite (probable)

Lepidolite, K(Li,Al)3(Si,Al)4O10(F,OH)2, in a granitic pegmatite matrix

Snowflake obsidian cabochon

Obsidian (volcanic glass), SiO₂-rich; white areas are cristobalite/spherulitic devitrification

Weathered porphyritic volcanic rock, likely andesite

Porphyritic andesite (tentative; plagioclase ± pyroxene/amphibole in a fine groundmass)

Quartz Vein in Sedimentary Rock

Silicon Dioxide (SiO2) with host Chert or Limestone

Quartz-rich pegmatite with mica

Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and muscovite/biotite mica

Pegmatitic granite (quartz–feldspar–mica rock)

Granitic pegmatite; primarily quartz (SiO₂), alkali/plagioclase feldspar, and minor mica, with iron-oxide staining

Greenschist

Greenschist (Chlorite Schist facies)

Amazonite

Potassium Feldspar (Microcline) - K(AlSi3O8)

Porphyritic Basalt (Drill Core)

Porphyritic Basalt with Plagioclase Phenocrysts

Amazonite

Microcline feldspar (KAlSi3O8)

Pegmatitic quartz–feldspar rock with dark mica

Granitic pegmatite; quartz (SiO₂), feldspar, and biotite mica

Porphyritic Basalt

Basalt with Feldspar Phenocrysts

Ocellar Rhyolite

Rhyolite (featuring orbicular/ocellar quartz and feldspar textures)

Porphyritic Rhyolite or Andesite (Porphyry)

Porphyritic igneous rock (Composition depends on exact mineralogy, often Rhyolite or Andesite)

Sandstone Pebbles

Arenite

Graphic Granite

Graphic Pegmatite

Quartz Geode in Sedimentary Host Rock

Silicon Dioxide (SiO2) in Carbonate Matrix

Epidote in Matrix (likely Amphibolite or Gneiss)

Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)) in Metamorphic Matrix