All rocks & minerals

Milky quartz

Quartz (SiO₂), likely massive vein quartz

Vesicular volcanic rock (likely scoria)

Scoria; vesicular basaltic to andesitic volcanic rock

Tumbled clear quartz

Quartz (SiO₂)

Fibrous gypsum (selenite/satin spar)

Gypsum, CaSO₄·2H₂O; fibrous variety

Banded gneiss

Gneiss, a foliated metamorphic rock; likely quartz–feldspar–mica gneiss

Banded gneiss

Foliated gneiss, likely quartz–feldspar–biotite gneiss

Weathered granite (probable)

Granite; a quartz–feldspar-rich intrusive igneous rock

Weathered granite

Granite, a coarse-grained quartz–feldspar plutonic rock

Fossil gastropod shell

Fossilized gastropod (class Gastropoda); species cannot be determined from this view

Iron-rich laterite (possibly ferruginous soilstone)

Laterite; chiefly iron oxides/oxyhydroxides such as goethite (FeO(OH)) and hematite (Fe₂O₃), with clay minerals and quartz

Granite

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

Calcite crystal cluster with matrix fragments

Calcite (CaCO₃), likely with minor iron-oxide staining and possibly associated quartz or feldspar

Iron-stained quartz-rich rock (likely sandstone)

Quartz-rich sandstone; exact identification is uncertain from the image

Likely sulfur-bearing rock (possibly native sulfur)

Native sulfur (S), though the image alone cannot confirm the specimen’s identity

Orange chalcedony (agate) in host rock

Microcrystalline quartz, SiO₂; likely iron-stained chalcedony

Granite

Granite, composed chiefly of quartz, feldspar, and mica

Fibrous gypsum (selenite/satin-spar variety)

Gypsum, CaSO₄·2H₂O

Likely milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Milky quartz in weathered host rock

Quartz (SiO₂), likely a massive vein-quartz fragment

Likely quartzite

Quartzite, composed predominantly of quartz (SiO₂)

Beaded bracelet, likely green aventurine and yellow citrine or dyed quartz

Quartz, SiO₂ (green aventurine may contain fuchsite inclusions)

Citrine-colored polished beads (material uncertain)

Possibly citrine quartz (SiO₂); the image alone cannot confirm the beads are natural stone rather than glass or another imitation.

Green Aventurine

Silicon dioxide with fuchsite inclusions (SiO2)

Quartzite

Quartzite, composed predominantly of quartz (SiO₂)

Fossil fish in limestone

Indeterminate fossil teleost fish preserved in calcareous sedimentary matrix

Iron-stained quartzite

Quartzite, composed predominantly of quartz (SiO₂), with iron-oxide staining

Polished rhodonite

Rhodonite, (Mn,Fe,Mg,Ca)SiO₃; commonly mixed with manganese oxides and other minerals

Tumbled brown jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂); exact variety cannot be confirmed from the image

Tumbled brown jasper

Jasper, an opaque, microcrystalline variety of quartz (SiO₂), often colored by iron oxides

Rounded brown river pebble, likely quartzite

Quartz-rich quartzite; exact identification requires examination beyond the photo

Polished dark granite (likely gneiss or granitic gneiss)

Quartz–feldspar–biotite granite/gneiss; exact identification requires examination of the specimen

Polished pink granite

Granite, a coarse-grained felsic intrusive igneous rock, composed mainly of feldspars, quartz, and dark mica or amphibole

Weathered granite

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

Likely bituminous coal

Coal, predominantly maceral-rich carbonaceous material (composition varies)

Yellow-brown jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly iron-stained

Banded gneiss

Foliated gneiss, likely quartz–feldspar–biotite gneiss

Chert (possibly jasper-bearing chert)

Microcrystalline quartz (SiO₂); chert, with iron-oxide staining

Rose quartz

Quartz, silicon dioxide (SiO₂)

Red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored chiefly by iron oxides

Petrified wood

Silicified fossil wood; commonly quartz (SiO₂) replacing woody tissue

Polished greenstone pebble

Likely serpentinite (serpentine-group minerals); identification from appearance alone is uncertain

Likely polished slate

Slate, a fine-grained metamorphic rock composed mainly of quartz, mica, and chlorite