Mineral In A Matrix (Likely Quartz Or Feldspar)

Dalmatian Jasper

Peralkaline Quartz Feldspar Porphyry

Likely granite

Granite; a coarse-grained rock composed mainly of quartz, feldspar, and mica or other dark minerals

Milky quartz (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Rounded quartz-rich pebble

Probable arkosic sandstone or weathered quartzite; exact identification is uncertain from the image

Biotite-rich gneiss (possibly mica schist)

Quartz–feldspar–biotite gneiss; mica-rich metamorphic rock

Weathered granite or granitic gneiss pebble

Quartz–feldspar–mica rock; exact identification is uncertain from the image

Weathered granite pebble

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

Weathered granite or granitic gneiss

Granite; primarily quartz (SiO₂), feldspar, and mica, possibly with metamorphic foliation

Cinnabar in Quartz

Silicon Dioxide (SiO2) with Mercury Sulfide (HgS) inclusions

Red Beryl in Rhyolite

Beryllium Aluminum Cyclosilicate with Quartz/Feldspar matrix (Be3Al2Si6O18)

Fluorite on matrix

Fluorite (CaF₂), likely on a pale quartz or calcite matrix

Porphyritic granitic pegmatite

Granitic pegmatite, composed chiefly of quartz, feldspar, and mica

Granite Cobble

Phaneritic Felsic Igneous Rock

Likely metamorphic schist or gneiss

Mica-rich quartz-feldspar schist/gneiss; exact identification requires testing

Weathered quartz-rich rock, likely granite or gneiss

Indeterminate granitic rock; mainly quartz, feldspar, and mica

Granitic Pegmatite

Pegmatite (Quartz: SiO2, Feldspar: KAlSi3O8, Mica: KAl2(AlSi3O10)(OH)2)

Dark volcanic rock, likely basalt

Basalt; primarily plagioclase feldspar and pyroxene, with possible olivine and alteration minerals

Weathered quartz-bearing rock fragment

Probably iron-stained quartz or quartz-rich sandstone; exact identification requires testing

Quartz crystal cluster in iron-stained matrix

Quartz (SiO₂), likely a drusy or small-vein crystal coating; exact host rock is unclear from the photo

Biotite-rich granite or granitic gneiss

Granite; primarily quartz, feldspar, and biotite mica

Dalmatian jasper beads

Commercially “Dalmatian jasper”; commonly spotted, silica-rich rock sold as jasper, though many specimens are feldspar-rich rock rather than true jasper (microcrystalline quartz).

Iron-stained fossiliferous rock, possibly fossil wood

Likely silicified/petrified wood in iron-rich silica matrix; exact identification requires microscopy

Iron-stained quartz cluster (likely druzy quartz)

Quartz, SiO₂, with iron-oxide staining

Gneiss

Feldspar–quartz–mica gneiss, locally amphibole-bearing

Feldspar (Orthoclase/Microcline)

Potassium Feldspar (KAlSi3O8)

Quartz-rich pegmatite

Pegmatitic granite, chiefly quartz (SiO₂), feldspar, and minor mica/iron-oxide staining

Milky quartz-rich rock, possibly quartzite

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

Weathered granitic boulder

Granite, typically composed of quartz, feldspar, and mica

Beryl (var. Heliodor or Aquamarine)

Beryllium Aluminum Cyclosilicate (Be3Al2Si6O18)

Smoky quartz crystal cluster

Quartz, silicon dioxide (SiO₂), likely smoky variety with possible feldspar or matrix inclusions

Likely granite

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

Weathered granite or granitic gneiss fragment

Quartz–feldspar–mica aggregate; likely granite (possibly gneiss)

Black tourmaline (schorl) in matrix

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Pink Granite

Phaneritic Felsic Igneous Rock (composed primarily of K-Feldspar, Quartz, and Mica)

Likely granite

Granite, a coarse-grained felsic intrusive igneous rock

Quartz crystal fragment (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Small gray rock fragment, likely granite or diorite

Uncertain; probable coarse-grained silicate rock dominated by feldspar and quartz, possibly biotite/hornblende

Weathered granitic rock fragment

Granite, predominantly quartz–feldspar–mica assemblage

Likely porphyritic basalt or andesite fragment

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

Polished orbicular jasper (likely ocean jasper)

Silicified volcanic rock; chiefly microcrystalline quartz (SiO₂), with feldspar and iron-rich alteration minerals

Weathered granitic pebble

Granite, likely quartz–feldspar–biotite aggregate

Pegmatitic mica-rich rock, likely lepidolite-bearing granite

Granitic pegmatite composed mainly of quartz, feldspar, and mica; pink-purple mica may be lepidolite or muscovite