All rocks & minerals

Jade

Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2) or Jadeite (NaAlSi2O6)

Black Tourmaline (Schorl)

Schorl (Complex sodium iron aluminum borosilicate)

Green Opal

Hydrated amorphous silica (SiO2·nH2O)

Coal

Biogenic sedimentary rock (Carbon)

Brecciated Jasper

Silicon dioxide (SiO2) microcrystalline quartz breccia

Scoria

Vesicular Mafic Igneous Rock

Hematite

Iron(III) oxide (Fe2O3)

Unakitized Granite

Granite / Altered Monzonite with Epidote

Quartz

Silicon Dioxide (SiO2)

Bismuthinite with Chalcopyrite and Quartz

Bismuthinite (Bi2S3) and Chalcopyrite (CuFeS2)

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Quartz

Silicon Dioxide (SiO2)

Dalmatian Jasper

Feldspar porphyry (Microcline and Quartz with Arfvedsonite spots)

Brachiopod Fossil in Matrix

Phylum Brachiopoda

Limestone

Calcium Carbonate (CaCO3)

Pyrite

Iron Sulfide (FeS2)

Pyrite Sun

Iron Sulfide (FeS2)

Granite

Intrusive Igneous Rock

Sandstone

Sedimentary Clastic Rock

Tumbled Quartz

Silicon Dioxide (SiO2)

Gold Nugget

Gold (Au)

Gold Nugget

Gold (Au)

Red Jasper

Microcrystalline quartz (SiO2) with iron oxide impurities

Carnelian (red chalcedony), possibly red agate or jasper

Chalcedony, a microcrystalline variety of quartz; silicon dioxide (SiO₂), commonly colored red-orange by iron oxides. The specimen may include opaque jasper or agate zones.

Banded malachite cabochon

Malachite, Cu₂CO₃(OH)₂; the dark bands may be manganese-oxide or other sulfide-rich matrix, and could also indicate a composite or treated specimen

Yellow calcite (tumbled honey or lemon calcite)

Calcite, calcium carbonate (CaCO₃), likely a yellow/orange calcite variety

Unakite (polished/tumbled)

Unakite, a hydrothermally altered granite composed mainly of epidote, pink potassium feldspar (orthoclase/microcline), and quartz

Tumbled carnelian agate with dark mineral inclusions

Carnelian, an orange variety of microcrystalline quartz (chalcedony), SiO₂; dark inclusions are likely iron oxides/hydroxides, possibly hematite, goethite, or a basaltic/matrix fragment

Turquoise cabochon

Turquoise; hydrated copper–aluminum phosphate, approximately CuAl6(PO4)4(OH)8·4H2O (composition varies)

White calcite (likely tumbled calcite or marble fragment)

Calcite, calcium carbonate (CaCO₃); if the specimen is granular and rock-like, it may be marble, a calcite-rich metamorphic rock

Weathered pegmatite or feldspar-rich granite fragment

Granitic pegmatite, composed mainly of potassium feldspar and quartz, with minor mica; exact identification is uncertain from the photograph

Tumbled sodalite with white calcite veining

Sodalite, Na8(Al6Si6O24)Cl2, commonly intergrown with calcite, CaCO3

Weathered fossiliferous limestone fragment, possibly fossil coral or shell material

Indeterminate carbonate fossil in calcitic limestone; likely composed mainly of calcite (CaCO₃), but species identification is not possible from this image alone

Iron-stained milky quartz

Quartz (SiO₂), mainly massive or vein quartz, with reddish-brown iron-oxide staining and possible minor feldspar or other vein minerals

Polished blue calcite sphere (tentative identification)

Calcite, CaCO₃; blue color generally results from trace impurities or inclusions

Tiger’s eye

Quartz variety, primarily silicon dioxide (SiO₂); fibrous quartz pseudomorph after crocidolite asbestos

Rose quartz cabochon (probable)

Quartz, silicon dioxide (SiO₂); pink color typically caused by trace elements and microscopic inclusions

Brecciated jasper (likely red-and-cream jasper)

Jasper, an opaque microcrystalline variety of quartz; primarily cryptocrystalline SiO₂ with iron-oxide staining and possible chalcedony/quartz veining

Tumbled pink calcite (probable)

Calcite, calcium carbonate (CaCO₃), likely manganocalcite variety

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

Rhodonite

Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix

Blue chalcedony cabochon (probable)

Chalcedony, cryptocrystalline quartz; silicon dioxide (SiO₂)