Mineral In A Matrix (Likely Quartz Or Feldspar)

Black-and-white spotted jasper (likely dalmatian jasper), polished beads

Commercially called Dalmatian jasper; typically a feldspar-rich rock with dark inclusions, not true jasper (microcrystalline quartz). Exact composition cannot be confirmed from the image.

Rhyolite

Rhyolite, felsic extrusive igneous rock

Weathered granitic gravel / decomposed granite

Granite-derived granitic saprolite; chiefly quartz, K-feldspar, plagioclase, and mica

Amethyst-bearing quartz with feldspar/mica matrix

Quartz, SiO₂, variety amethyst; likely pegmatitic matrix

Black tourmaline in matrix

Schorl, NaFe3Al6(BO3)3Si6O18(OH)4

Polished ocean jasper cabochon

Orbicular jasper (microcrystalline quartz, SiO₂)

Iron-stained quartz with possible feldspar

Quartz (SiO₂), likely with limonite/goethite staining and feldspar matrix

Granite with Tourmaline or Biotite

Phaneritic Igneous Rock (Granoid)

Quartz-rich mineral specimen, possibly druzy quartz

Quartz (SiO₂), possibly with carbonate or feldspar matrix

Banded metamorphic rock, likely gneiss or banded amphibolite

Quartz–feldspar–biotite gneiss or amphibolite; exact identification requires thin-section or mineral tests

Weathered gray sandstone or siltstone

Clastic siliciclastic rock, primarily quartz and feldspar grains cemented by silica or carbonate

Quartz-veined metamorphic rock, likely schist or gneiss

Micaceous quartz-feldspar rock; probable mica schist/gneiss with quartz veins

Tumbled granite (likely weathered granite pebble)

Granite; chiefly quartz, feldspar, and mica/amphibole

Porphyritic Rhyolite

Rhyolite (Porphyritic texture)

Amethyst-bearing quartz geode or vein specimen

Quartz, SiO₂; purple coloration from trace iron and irradiation

Likely weathered granite or granitic gneiss

Granite: quartz, feldspar, and mica; possibly weakly foliated gneiss

Black-and-white gneiss

Gneiss, chiefly quartz–feldspar with dark biotite/amphibole bands

Weathered quartz-bearing rock, possibly granite or pegmatite

Likely quartz–feldspar rock; exact mineral identification is uncertain from the photograph

Mica-bearing pegmatite

Granitic pegmatite composed mainly of quartz, feldspar, and biotite/muscovite mica

Milky quartz (rough quartz specimen)

Quartz, silicon dioxide (SiO₂)

Quartz-rich pegmatite

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

Granite pebble

Granite; predominantly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Smoky quartz with feldspar matrix

Quartz (SiO₂), likely intergrown with potassium feldspar and mica

Mica-rich rock spheres (possibly pegmatitic mica nodules)

Mica-rich granitic/pegmatitic material; exact identification is uncertain from the photograph

Tumbled granite pebble

Granite, mainly quartz (SiO₂), feldspar, and minor biotite/hornblende

Rounded basaltic conglomerate / breccia pebble

Basalt-rich polymict conglomerate, with plagioclase, pyroxene, and altered mafic minerals

Pink-and-white quartz-rich rock, likely rose quartz matrix

Quartz (SiO₂), possibly intergrown with feldspar or chalcedony

Graphic Granite (or Pegmatite)

Graphic Granite

Tumbled quartz-rich stone, likely rose quartz

Quartz (SiO₂), probably iron-bearing rose quartz

Quartz geode/drusy quartz cluster

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

Milky quartz with iron-oxide staining and dark matrix

Quartz (SiO₂), likely with hematite/goethite and minor feldspar or mica

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), likely in a quartzite or silicified matrix

Likely quartz-rich rock fragment

Quartz (SiO₂), possibly in a feldspar-bearing granite or pegmatite matrix

Amazonite

Triklinic Potassium Feldspar (KAlSi3O8)

Likely weathered granite or pegmatitic rock

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

Likely weathered quartz-rich stone

Indeterminate; possibly quartz-bearing granite or milky quartz

Biotite-bearing granite or granitic gneiss

Quartz–feldspar granite with biotite mica; possibly weakly foliated gneiss

Prase Quartz on Feldspar

Quartz (Silicon Dioxide, SiO2) with Hedenbergite inclusions on Potassium Feldspar (KAlSi3O8)

Chrysocolla-bearing rock (likely chrysocolla in quartz/limonite matrix)

Chrysocolla, hydrated copper aluminosilicate: (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O

Small rough mineral specimen, likely quartz-bearing stone

Indeterminate from image; possibly quartz (SiO₂) with iron-oxide staining

Porphyritic Basalt

Amygdaloidal Porphyritic Basalt

Likely porphyritic igneous rock (possibly granite or rhyolite)

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