Mineral In A Matrix (Likely Quartz Or Feldspar)

Sandstone Pebbles

Arenite

Granite with Quartz inclusion

Granite (Mainly SiO2, KAlSi3O8, NaAlSi3O8)

Smoky quartz-bearing pegmatitic rock

Quartz, SiO₂, likely with feldspar and mica inclusions

Weathered polymictic conglomerate or breccia

Polymictic conglomerate/breccia, likely iron-stained and quartz-bearing

Likely weathered feldspar-rich stone

Feldspar, probably microcline or orthoclase (KAlSi₃O₈), possibly altered pegmatite material

Mixed polished rock/mineral specimens

Indeterminate from image; likely quartz-bearing material with iron-oxide staining and possibly mica-rich schist

Unakite (likely)

Epidote–pink feldspar–quartz rock; commonly termed unakite

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; mainly quartz, feldspar, and biotite/hornblende

Quartz with Feldspar and Matrix

Silicon Dioxide (SiO2) with Potassium/Plagioclase Feldspar

Orbicular gneiss (likely augen gneiss)

Quartz–feldspar–biotite gneiss; locally termed augen gneiss

Pyrite in Matrix (likely Quartz or Coal)

Iron Sulfide (FeS2)

Weathered quartz-rich pebble, possibly granite or pegmatite

Quartz (SiO₂) with probable feldspar and minor mica/iron-oxide inclusions

Rose quartz–bearing pegmatite (probable)

Quartz (SiO₂) in a granitic pegmatite matrix, possibly with feldspar

Porphyritic granite boulder

Granite, commonly quartz–alkali feldspar–plagioclase with biotite/hornblende

Quartz (on matrix)

Quartz (Silicon Dioxide, SiO₂)

Quartz-rich rock, likely smoky quartz with feldspar

Quartz (SiO₂), possibly in a granitic or pegmatitic matrix

River Stone (Sandstone or Siltstone)

Sedimentary Rock (Clastic)

Red porphyritic volcanic rock, likely rhyolite or andesite

Porphyritic rhyolite–andesite; predominantly quartz/feldspar with iron-oxide staining

Granite Pebble

Granite (Phaneritic Igneous Rock)

Quartz-veined dark metamorphic rock

Likely quartz-bearing hornfels, amphibolite, or altered basalt; exact identification requires a fresh surface and tests

Quartz-rich crystalline rock, likely drusy quartz on matrix

Quartz (SiO₂), possibly intergrown with calcite or feldspar matrix

Quartz-bearing metamorphic rock, likely quartzite or hornfels

Quartz (SiO₂) in a fine-grained silicate matrix; exact rock identification requires testing

Weathered granitic or feldspathic pebble

Likely granite/granodiorite; quartz–feldspar–mica aggregate

Quartz geode

Microcrystalline quartz (chalcedony) with drusy quartz crystals; SiO₂

Likely coarse-grained igneous rock, possibly granite or gabbro

Granite (quartz–feldspar–mica) or gabbro (plagioclase–pyroxene); exact identification requires a fresh surface and testing

Graphic Granite

Graphic Granite (Pegmatite)

Metamorphic rock with large feldspar crystals (likely porphyroblastic gneiss)

Feldspar-porphyroblastic gneiss; likely quartz and feldspar with mica/amphibole, identification from image only

Smoky Quartz on Feldspar (Granite Pegmatite)

Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)

Polished gabbro or basalt with quartz/calcite veining

Mafic igneous rock; chiefly plagioclase and pyroxene, with light veins of quartz or calcite

Uncertain dark-and-white rock fragment

Likely a mixed lithic specimen, possibly quartz-bearing granite or ore; exact identification is not possible from the photograph

Smoky Quartz in Matrix (Pegmatite)

Silicon Dioxide (SiO2) with Potassium Feldspar and Biotite mica

Garnet-bearing granite or granitic gneiss

Quartz–feldspar granite with almandine garnet (Fe₃Al₂Si₃O₁₂), possibly garnet-bearing gneiss

Quartz-bearing weathered rock

Massive to drusy quartz (SiO₂), possibly in a feldspathic or carbonate host

Vein-bearing metamorphic rock, likely gneiss or schist

Quartz-feldspar–mica metamorphic rock; exact identification requires testing

Conglomeratic concrete or asphalt aggregate surface with dark bituminous chunks

Polymictic gravel aggregate; dark pieces likely bitumen/asphalt, not a natural rock

Porphyritic granite (granite porphyry)

Quartz–feldspar porphyritic granite; mainly quartz, K-feldspar, plagioclase, and biotite/hornblende

Amazonite

Microcline Feldspar (KAlSi3O8)

Rhyolite

Rhyolite

Mica-bearing quartz rock, likely pegmatite

Quartz–feldspar–mica pegmatite; visible mica is probably biotite or muscovite, SiO₂ quartz

Granitic Pegmatite with Schorl

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

Milky quartz vein in altered host rock

Quartz (SiO₂), likely with feldspar, mica, and iron-oxide alteration

Polished pink tourmaline in quartz (likely tourmalinated quartz)

Quartz (SiO₂) with pink lithium-rich tourmaline, commonly elbaite