Mineral In A Matrix (Likely Quartz Or Feldspar)

Weathered porphyritic volcanic rock (likely basaltic andesite)

Porphyritic basaltic andesite; mineral assemblage likely plagioclase, pyroxene, and iron oxides

Quartz-rich feldspathic rock, likely rose quartz-bearing granite or pegmatite

Granite/pegmatite composed mainly of quartz (SiO₂) and feldspar, with iron-oxide staining

Porphyritic Basalt

Porphyritic Mafic Volcanic Rock

Graphic Granite

Graphic Granite (Quartz/Feldspar intergrowth)

Porphyritic Basalt (likely artificially dyed or altered)

Basalt with plagioclase phenocrysts (likely treated)

Carved Gemstone Mushroom

Quartz / Feldspar composite (Carved lapidary art)

Porphyritic basalt (likely amygdaloidal basalt)

Basalt containing larger plagioclase crystals and pale vesicle-fill minerals, commonly calcite, zeolite, or quartz

Weathered porphyritic volcanic rock

Likely porphyritic andesite or dacite, with plagioclase phenocrysts in a fine-grained volcanic groundmass

Quartz Vein in Hematitic Siltstone

Hydrothermal Quartz (SiO2) in Ferriferous Matrix

Rhodonite-bearing metamorphic pebble

Rhodonite (MnSiO₃) in manganese-rich silicate rock, possibly with quartz or feldspar

Granite

Phaneritic Plutonic Felsic Rock (Quartz/Feldspar/Mica)

Granite (rounded glacial cobble)

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

Porphyritic Andesite

Andesite (Porphyritic texture)

Fluorite in Matrix

Fluorite (CaF2) within a host rock matrix

Sandstone with Magnetite and Iron Staining

Clastic Sedimentary Rock (contains Fe3O4 and Limonite/Hematite)

Small reddish-brown mineral fragment, likely quartz-bearing rock

Indeterminate; possibly iron-stained quartz or feldspar-rich stone

Porphyry

Porphyritic Igneous Rock

Porphyritic volcanic rock, likely andesite

Porphyritic andesite; mainly plagioclase, pyroxene/amphibole, and volcanic groundmass

Dark mafic igneous rock, likely basalt or gabbro

Basalt–gabbroic rock; chiefly plagioclase feldspar and pyroxene, possibly olivine

Quartz-bearing granitic pegmatite (probable)

Mostly quartz (SiO₂) with feldspar and mica; exact minerals uncertain from one image

Weathered sandstone pebble

Quartz-rich sandstone, likely arkosic or lithic sandstone

Granitic Pegmatite with Schorl Tourmaline

Granitic Pegmatite (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4)

Quartzite in Conglomerate

Clastic Sedimentary Rock with Silicon Dioxide (SiO2) inclusions

Garnet-bearing metamorphic rock, possibly garnet amphibolite or mica schist

Almandine garnet (Fe₃Al₂Si₃O₁₂) in a mafic, amphibole–feldspar-rich matrix

Quartz-rich breccia or altered granite fragment

Polymineralic quartz–feldspar rock, likely hydrothermally altered granite/pegmatite

Amazonite in Matrix

Potassium Feldspar (Microcline), KAlSi3O8

Pegmatite (with Muscovite Mica and Quartz)

Granitic Pegmatite (chiefly KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)

Quartz crystal with associated mica or feldspar

Quartz (SiO₂), with possible muscovite mica and feldspar inclusions

Porphyritic rhyolite (likely weathered volcanic rock)

Rhyolite, a volcanic equivalent of granite; chiefly quartz and alkali feldspar in a fine-grained groundmass

Quartz-veined metamorphic rock

Likely quartz-veined schist or gneiss; exact identification requires closer examination

Quartz-rich pegmatite with green epidote or chlorite

Pegmatitic quartz–feldspar rock, likely containing epidote (Ca₂(Al,Fe)₃Si₃O₁₂(OH)) and/or chlorite

Quartz-rich pegmatite (likely rose/iron-stained quartz)

Quartz, SiO₂, in a coarse granitic pegmatite matrix; possibly with feldspar and mica

Biotite-rich granite or gneiss

Feldspar–quartz–biotite granitoid; possibly metamorphosed granite (orthogneiss)

Granitic Pegmatite with Tourmaline

Granite (Feldspar/Quartz matrix) with Schorl (NaFe2+3Al6Si6O18(BO3)3(OH)3OH)

Rounded white pebble, likely quartz or feldspar

Most consistent with milky quartz (SiO₂), though altered feldspar or calcite is possible from the image

Dalmation Stone (frequently called Dalmatian Jasper)

Peralkaline Quartz-Feldspar Rock

Pegmatitic granite

Coarse-grained granite/pegmatite, chiefly quartz, feldspar, and mica

Chalcedony breccia (possibly agate with drusy quartz)

Microcrystalline quartz, SiO₂, with crystalline quartz and dark matrix/inclusions

Green tourmaline (likely elbaite)

Tourmaline-group cyclosilicate; likely elbaite, Na(Li,Al)3Al6(BO3)3Si6O18(OH)4

Agate-bearing rhyolite (likely polished/cut specimen)

Silica-rich volcanic rock containing microcrystalline quartz/chalcedony, SiO₂, with feldspar and possible iron oxides

Biotite-rich granite or granodiorite

Felsic intrusive igneous rock; quartz–feldspar–biotite aggregate

Likely granite

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