Mineral In A Matrix (Likely Quartz Or Feldspar)

Polished orbicular granite

Granite, chiefly quartz, alkali feldspar, plagioclase, and biotite/amphibole

Banded gneiss

Felsic biotite–quartz–feldspar gneiss

Black Tourmaline (Schorl) on Quartz

NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)

Granite, possibly granodiorite

Coarse-grained felsic plutonic rock; chiefly quartz (SiO₂), potassium feldspar and plagioclase feldspar, with biotite and/or hornblende

Porphyritic Basalt (with Olivine or Quartz phenocryst)

Porphyritic Basalt (Mafic Extrusive)

Orthoclase Feldspar (Potassium Feldspar)

KAlSi3O8 (Potassium Aluminum Silicate)

Small quartz-rich pebble

Quartz (SiO₂), possibly quartzite or weathered granite fragment

Weathered iron-stained quartzite or sandstone cobble

Quartzite (quartz-rich rock), possibly ferruginous sandstone

Granite

Granite (composed primarily of silica-rich minerals like quartz and feldspar)

Porphyritic Andesite

Andesite

Olivine

Olivine group (Mg, Fe)2SiO4

Unakite

Altered Granite (Epidotized Feldspar with Quartz)

Quartz-veined Greywacke

Lithic Wacke with Siliceous Veins

Quartz-rich breccia or vein quartz with iron staining

Microcrystalline to crystalline SiO₂, likely quartz with iron oxides/hydroxides and altered host rock

Sandstone Pebble

Sandstone (Silicon dioxide-rich clastic sedimentary rock)

Quartz-bearing Pegmatite with Metallic Sulfides

Pegmatite / Quartz-Feldspar Matrix with Pyrite and Mica

Sandstone (Ferruginous)

Arenite with Iron Oxide matrix

Dalmatian Stone (Dalmation Jasper)

Aplite with Arfvedsonite inclusions

K2 Jasper (K2 Stone)

Azurite in Granite / Quartzite

Granite (likely biotite granite)

Coarse-grained granitic rock; chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende

Feldspar (specifically Orthoclase or Plagioclase)

Potassium Aluminum Silicate (KAlSi3O8) or Sodium/Calcium Aluminum Silicate

Likely quartz-rich rock or weathered granite fragment

Granite-like quartz–feldspar aggregate; exact identification requires testing

Milky quartz

Quartz (SiO₂), likely massive or drusy quartz

Likely weathered quartz-rich rock fragment

Uncertain; possibly granitic pegmatite or quartz-bearing metamorphic rock

Weathered granite or granitic gneiss

Granite; primarily quartz, feldspar, and mica (exact identification uncertain from the photo)

Tumbled quartz-rich pebble

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

Gneiss (Banded Gneiss Cobble)

Gneiss

Quartz Vein in Siltstone

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

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

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

Basalt with Quartz Veins

Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene) with SiO2 inclusions

Granite

Granite (Felsic Intrusive Igneous Rock)

Quartz cluster, possibly druzy quartz on matrix

Quartz (SiO₂), likely microcrystalline to coarse crystalline; associated matrix uncertain

Rounded granitic gneiss pebble

Felsic orthogneiss, composed mainly of quartz, feldspar, and mica

Granite Pebble (Salt and Pepper Granite)

Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Biotite/Amphibole)

Polished granite pebble

Granite, commonly quartz–feldspar–mica aggregate

Quartz Vein in Gneiss/Granite

Silicon Dioxide (SiO2) in Feldspar-Quartz Gneiss host rock

Weathered quartz-rich metamorphic rock (probable quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible mica, feldspar, and iron-oxide impurities

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitoid; possibly gneiss if the visible layering is tectonic

Red Beryl in Rhyolite

Beryllium Aluminum Cyclosilicate with Quartz/Feldspar matrix (Be3Al2Si6O18)

Polished dark stone, likely labradorite or dark agate

Likely feldspar-rich labradorite (plagioclase) or microcrystalline quartz (chalcedony); exact identification requires testing

Quartz-rich rock, possibly milky quartz

Quartz (silicon dioxide, SiO₂), possibly with feldspar or mica inclusions

Granite

Granite (Phaneritic intrusive igneous rock)