Mixed (Sedimentary, Igneous, And Metamorphic)

Polished granite pebble

Granite; chiefly quartz, feldspar, and mica/amphibole

Magnetite

Magnetite (Fe3O4)

Jasper-Quartz Conglomerate / Chert

Siliceous Sedimentary Rock (SiO2)

Mixed rounded gravel and pebbles

Polymictic clasts, likely including granite, basalt, quartzite, sandstone, and schist

Blue Apatite

Apatite-(CaF), Ca5(PO4)3F (Calcium Fluorophosphate)

Graphite-bearing schist (probable)

Graphite–quartz–mica schist; chiefly graphite (C), quartz (SiO₂), and mica

Tumbled green aventurine and/or serpentine

Quartz variety aventurine (SiO₂) and possibly serpentine-group minerals

Mixed Gemstones and Minerals

Mixed Silicates and Oxides (Quartz/Amethyst, Aventurine, Sodalite, Chert, Jasper)

Carnelian and Mixed Agates

Cryptocrystalline Quartz (SiO2 with Iron Oxide impurities)

Unakite (Epidotized Granite)

Epidotized Granite (mixture of Orthoclase, Epidote, and Quartz)

Barite

Barium Sulfate (BaSO4)

Diorite (River Rock/Cobble)

Intermediate Plutonic Igneous Rock (Diorite)

Pink Granite

Granite (Phaneritic Acidic Igneous Rock)

Sandstone (lithic wake/graywacke variety)

Arenite/Greywacke (SiO2 with lithic fragments)

Unidentified coarse-grained rock fragments

Likely granite or granitic rock; exact identification is uncertain from the photograph

Feldspar (Granite Pegmatite matrix)

Potassium Feldspar (KAlSi3O8) / Quartz Mixture

Metallic sulfide mineral specimen, likely pyrite-bearing ore

Likely pyrite (FeS₂), possibly mixed with other sulfides or host rock

Small quartz-rich mineral fragment

Quartz (SiO₂), possibly milky or chalcedonic quartz

Conglomerate

Conglomerate (clastic sedimentary rock)

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

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

Conglomerate

Conglomerate (Sedimentary rock containing rounded clasts)

Mixed rough mineral specimens, likely calcite with prehnite/zeolite

Calcite (CaCO₃), with probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂) and/or zeolite-group minerals

Concrete-like aggregate surface with embedded rock fragments

Anthropogenic concrete or exposed aggregate; not a natural rock specimen

Fuchsite on Quartz

Muscovite (KAl2(AlSi3O10)(OH)2) with Chromium impurities

Blue Quartz (Dumortierite Quartz)

SiO2 with inclusion of AlAl6BSi3O18

Jasper (Green Jasper/Heliotropic Chert)

Silicon Dioxide (SiO₂)

Quartz-rich rock, possibly iron-stained quartz or quartzite

Quartz (SiO₂), likely with iron-oxide inclusions; exact identification requires testing

Sodalite

Sodium Aluminum Silicate Chloride (Na8(Al6Si6O24)Cl2)

Polished quartz-rich feldspar rock, possibly orbicular granite

Granite or granitic pegmatite; chiefly quartz (SiO₂), feldspar, and dark biotite/amphibole

Gray granite or granitic gneiss gravel

Granite; primarily quartz, feldspar, and mica (exact identification is uncertain from the photograph)

Granodiorite

Granodiorite (intermediate intrusive igneous rock containing plagioclase, quartz, and K-feldspar)

Polymict conglomerate

Clastic conglomerate, likely polymictic pebble conglomerate

Granite pebble

Granite; primarily quartz, alkali feldspar, plagioclase, and dark mica/amphibole

Polished/rounded granite cobble

Granite, chiefly quartz (SiO₂), feldspar, and mica/amphibole

Tiger's Eye / Hawk's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Pyrite Nodules / Weathered Pyrite

Iron Sulfide (FeS2)

Granite (Pink/Red)

Phaneritic Igneous Rock (Rich in K-Feldspar)

K2 Jasper (K2 Granite)

Azulite in Granite (Quartz + Feldspar + Biotite + Azurite)

Quartz

Silicon dioxide (SiO2)

Granite or Granitoid River Rock

Granite

Granite Pegmatite

Pegmatite (Quartz, Feldspar, Mica)

Red Agate Sphere (or Banded Jasper/Agate)

Silicon Dioxide (SiO2) - Microcrystalline Quartz