Mineral In A Matrix (Likely Quartz Or Feldspar)

Granite

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica

Weathered porphyritic volcanic rock

Likely porphyritic andesite or basalt; exact identification requires a fresh surface and testing

Quartz Crystal Cluster on Matrix

Silicon Dioxide (SiO2)

Tumbled milky quartz (likely quartzite or chalcedony-rich stone)

Quartz, SiO₂

Small weathered quartz-rich pebble

Likely quartz (SiO₂), possibly quartzite or feldspar-bearing rock

Porphyritic basaltic-andesite

Porphyritic intermediate volcanic rock; chiefly plagioclase and pyroxene/amphibole, with altered mafic minerals and iron oxides

Weathered pink granite

Granite, chiefly quartz, feldspar, and mica

Coarse-grained mica-bearing metamorphic rock, likely schist

Mica schist, probably muscovite–biotite schist with quartz and feldspar

Mica-bearing quartz rock (likely pegmatite)

Quartz–feldspar–mica pegmatite; dark mica is probably biotite, possibly muscovite or chlorite

Small pale mineral fragment

Unidentified; possibly quartz, calcite, or feldspar

Polished pink feldspar pebble

Microcline or orthoclase feldspar, KAlSi₃O₈, possibly with quartz or mica inclusions

Quartz with Tourmaline and Iron Staining

Silicon Dioxide (SiO2) with Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH)

Quartz vein in host rock

Quartz (SiO₂), likely milky quartz with iron-oxide staining; host rock is uncertain from the photo

Basalt with Plagioclase Porphyry

Porphyritic Basalt

Pyritic Sandstone

Clastic Sedimentary Rock (Pyrite-bearing Sandstone)

Mica-rich pegmatite (likely muscovite-bearing quartz–feldspar rock)

Granitic pegmatite composed mainly of quartz, feldspar and muscovite; exact identification requires testing

Milky quartz-bearing rock, possibly quartzite

Quartz (SiO₂), likely in a quartzite or quartz-rich metamorphic matrix

Polymictic breccia, possibly volcanic breccia

Polymictic clastic breccia; likely a matrix-supported breccia containing lithic fragments, quartz, feldspar, and dark mafic minerals

Mica-rich granitic rock fragment

Likely granite or granitic pegmatite, composed mainly of quartz and feldspar with reflective mica

Rounded granite pebble

Granite, chiefly quartz, feldspar, and mica

Likely pink granite

Granite, a coarse-grained felsic intrusive igneous rock

Small banded metamorphic rock fragment

Indeterminate foliated metamorphic rock; possibly mica schist or gneiss

Probable weathered granite or granitic gneiss

Granite/granitic gneiss; mainly quartz, feldspar, and mica

Tumbled mottled stone, likely serpentine or jasper

Probable serpentine-group mineral (Mg₃Si₂O₅(OH)₄) or fine-grained jasper; identification is limited by the image

Porphyritic basalt with weathering or mineral-filled veins

Basalt, likely plagioclase-porphyritic; composition dominated by plagioclase and pyroxene with possible secondary quartz or calcite

Weathered porphyritic pebble

Likely porphyritic volcanic rock, possibly andesite or rhyolite

Small rounded pebble, likely quartz-rich stone

Indeterminate from photograph; possibly microcrystalline quartz (SiO₂) or a weathered silicate pebble

Quartz with Feldspar

Silicon Dioxide (SiO2) with Potassium Feldspar (KAlSi3O8)

Quartz-rich pegmatite (likely milky quartz with feldspar)

Pegmatitic quartz–feldspar rock; primarily SiO₂ quartz with K-feldspar/plagioclase

Granite

Granite (composed of Quartz, Feldspar, and Mica)

Weathered granite or granitic gneiss fragment

Granite, predominantly quartz, feldspar, and dark mica/amphibole

Tumbled quartz-rich stone, likely druzy quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Weathered pink granite or granitic rock

Granite; chiefly quartz (SiO₂), feldspar, and mica/amphibole

Rounded granite pebble

Granite; chiefly quartz, feldspar, and mica

Rough chalcedony (likely agate/quartz vein)

Chalcedony, microcrystalline SiO₂; possibly agate with iron-oxide-stained host rock

Dalmatian Stone

Peralkaline Quartz-Feldspar Rock with Arfvedsonite

Pegmatitic quartz–feldspar rock

Quartz and feldspar-rich pegmatite (exact identification requires testing)

Sandstone

Arenite (SiO2 based with mineral cement)

Graphic Granite

Graphic Granite (Granitic Pegmatite)

Graphic Granite

Pegmatitic Quartz-Feldspar Granite

Tumbled milky quartz

Quartz (SiO₂), likely milky quartz

Tumbled granite or granitic pebble

Granite, a quartz–feldspar–mica plutonic rock