Mineral In A Matrix (Likely Quartz Or Feldspar)

Weathered brown-gray igneous rock, likely basaltic andesite

Porphyritic basaltic andesite; probable plagioclase–pyroxene volcanic rock

Conglomeratic volcanic breccia

Lithic volcanic breccia, likely andesitic or basaltic

Weathered feldspathic rock, likely granite or granitic pegmatite

Quartz–feldspar–mica aggregate; exact species indeterminate from the image

Polished leopard-skin jasper (likely orbicular rhyolite)

Orbicular rhyolite, a silica-rich volcanic rock with feldspar and quartz; exact identification from the photo is uncertain

Likely quartz-bearing mineral aggregate

Quartz (SiO₂), possibly mixed with mica or feldspar

Iron-stained quartz-rich rock, possibly weathered granite or quartzite

Uncertain from image; likely quartz (SiO₂) with feldspar and iron-oxide staining

Weathered basalt (likely altered basalt)

Basalt, chiefly plagioclase feldspar and pyroxene, with possible chlorite/epidote alteration

Banded greenstone or altered basalt

Chlorite–epidote amphibolite/greenstone; exact identification requires testing

Dalmatian Stone (Dalmatian Jasper)

Peralkaline Aplite (Quartz, Feldspar, and Arfvedsonite composition)

Porphyritic Basalt

Basalt with Feldspar Phenocrysts

Iron-stained quartz/pegmatite fragment

Quartz (SiO₂) with iron-oxide/hydroxide staining, possibly feldspar matrix

Fossil gastropod in granite-like stone

Gastropoda indet.; enclosing rock likely polished granite or gneiss

Dalmatian Jasper

Peralkaline Feldspar Rhyolite

Agate Jasper

Cryptocrystalline Quartz (SiO2) with impurities

Weathered graywacke or sandstone with a dark mineral-rich vein

Likely lithic graywacke/sandstone; dark material may be quartz, iron-manganese oxide, or sulfide mineralization

Granite Cobble

Felsic intrusive igneous rock

Mica-bearing metamorphic rock, likely schist

Muscovite–biotite schist, possibly phyllite

Snowflake obsidian cabochon

Obsidian (volcanic glass), SiO₂-rich; white areas are cristobalite/spherulitic devitrification

Black-and-white tourmaline (schorl in quartz)

Schorl, a sodium iron tourmaline: NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄; the pale material may be quartz or feldspar.

Quartz-Veined Sandstone

Quartz-veined Arenite

Orbicular gabbro (likely oceanic orbicular rock)

Orbicular gabbro, composed chiefly of plagioclase feldspar and pyroxene, with concentric orbicules

Amazonite

Microcline feldspar (KAlSi3O8)

Quartz-bearing granite or granitic pegmatite

Crystalline quartz (SiO₂) with feldspar and dark mica/amphibole; likely weathered granite

Mica-rich pegmatite, likely muscovite schist or granite

Muscovite-dominant quartz–feldspar rock; approximate mica formula KAl₂(AlSi₃O₁₀)(OH)₂

Quartz–feldspar pegmatite fragment

Granitic pegmatite; chiefly quartz (SiO₂) and feldspar, with possible mica/amphibole

Speckled granite, likely weathered or polished

Granite; quartz–alkali feldspar–plagioclase–biotite aggregate

Quartz Geode in Sedimentary Host Rock

Silicon Dioxide (SiO2) in Carbonate Matrix

Brecciated polymictic rock, possibly impact breccia

Polymictic breccia; exact lithology indeterminate from image

Vesicular basalt (possibly slag-like volcanic rock)

Basalt, predominantly plagioclase–pyroxene–olivine; exact identification is uncertain from the photograph

Epidote in Matrix (likely Amphibolite or Gneiss)

Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)) in Metamorphic Matrix

Garnet-bearing granite or pegmatitic granitic rock

Coarse-grained granitoid, likely granite or pegmatite, composed mainly of quartz and feldspar with almandine/spessartine garnet and dark biotite or amphibole

Polymict conglomerate

Clastic conglomerate, likely polymictic and matrix-supported

Quartz-rich weathered rock, possibly quartz geode or vuggy quartz vein

Quartz (SiO₂), likely with iron-oxide staining and possible feldspar/calcite matrix

Quartz-rich pegmatite or hydrothermal quartz specimen

Quartz (SiO₂) in a coarse felsic host, possibly pegmatitic granite with feldspar and mica

Polished dark greenstone with quartz vein

Likely chlorite-rich metabasalt or greenschist with a quartz–feldspar vein

Iron-stained quartz-rich rock, likely quartz vein material

Quartz (SiO₂), with iron-oxide staining and probable feldspar/matrix minerals

Coarse-grained granite

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

Unidentified weathered rock fragment

Likely granitic or feldspathic rock; exact identification requires clearer imaging and testing

Porphyritic Basalt (Drill Core)

Porphyritic Basalt with Plagioclase Phenocrysts

Banded River Pebble (Gneiss or Quartz-Veined Basalt)

Polished River Siltstone or Quartzite Gneiss

Quartz-bearing pegmatitic rock with feldspar

Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and mica

Porphyritic granite (likely orbicular/porphyritic granitoid)

Quartz–feldspar granitoid; commonly composed of K-feldspar, plagioclase, quartz, and biotite/hornblende