Uncertain

Vesicular volcanic rock, likely scoria

Scoria; predominantly basaltic composition (plagioclase, pyroxene, olivine, and volcanic glass)

Fluorescent glassy mineral specimen, possibly hyalite opal

Hyalite (hydrated amorphous silica, SiO₂·nH₂O), tentative

Iron-stained quartz-rich rock, possibly goethite-bearing quartz

Quartz (SiO₂) with iron oxides/hydroxides, likely goethite or limonite

Polished golden-brown banded stone, likely tiger’s eye

Tiger’s eye (quartz with fibrous crocidolite pseudomorphs; SiO₂)

Polished chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂; chalcedony with possible iron-oxide and/or manganese dendrites

Iron meteorite (probable, possibly industrial iron slag)

Fe–Ni metallic alloy, commonly kamacite and taenite

Weathered granite fragment

Granite; primarily quartz, alkali feldspar, plagioclase, and minor biotite/hornblende

Pink granite (probable)

Granite, composed mainly of quartz, alkali feldspar, and plagioclase with minor mica

Blue cabochon ring stone, likely sapphire or synthetic blue corundum

Corundum (Al₂O₃), possibly chromium/iron-titanium-bearing sapphire

Rhyolite or fine-grained volcanic rock

Rhyolite ( felsic volcanic rock; commonly quartz + alkali feldspar)

Dark mafic metamorphic rock, likely amphibolite

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Tumbled black stone, likely obsidian

Obsidian (natural volcanic glass; mainly silica-rich rhyolitic composition)

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and biotite/hornblende

Rose quartz (probable)

Quartz, SiO₂; pink coloration typically from trace inclusions or irradiation-related defects

Milky quartz-bearing rock, possibly quartzite or quartz vein

Quartz (SiO₂), likely with feldspar and minor iron-oxide inclusions

Likely raw garnet-bearing metamorphic rock

Garnet schist or garnet amphibolite; probable almandine garnet (Fe₃Al₂Si₃O₁₂)

Weathered vesicular limestone or calcareous tuff

Porous calcite-rich carbonate rock; composition likely predominantly CaCO₃ (calcite), with iron-oxide staining and possible silica/clay impurities

Possible tektite or volcanic glass specimen

Natural silica glass; composition commonly near SiO₂, but exact identification requires chemical testing

Red jasper / iron-rich chert

Microcrystalline quartz (SiO₂) colored by hematite/goethite

Blue glassy gemstone cabochon, likely dyed chalcedony or glass

Uncertain; possible dyed chalcedony (microcrystalline quartz, SiO₂)

Polished brown pebble, possibly agate or jasper

Uncertain; likely microcrystalline quartz (SiO₂) if agate/jasper

Small dark rock fragment (likely basalt or slag)

Tentatively basalt; exact identification is uncertain from the photograph

Yellow faceted gemstone, likely citrine or yellow sapphire

Uncertain; probable quartz (SiO₂) or corundum (Al₂O₃)

Dark fine-grained rock fragment

Probably basalt or basaltic scoria; visual identification is uncertain

Small reddish-brown mineral fragment

Uncertain; possibly iron-stained quartz, feldspar, or garnet

Blue-dyed tumbled stone, likely calcite or quartz

Uncertain; commonly dyed quartz (SiO₂) or calcite (CaCO₃)

Likely garnet-bearing metamorphic fragment

Uncertain; possibly almandine garnet in mica schist or amphibolite

Tumbled dark metallic mineral specimen

Likely hematite or magnetite; identification is uncertain from the photograph

Tumbled milky quartz (probable quartzite or chalcedony pebble)

Quartz, SiO₂; exact variety uncertain from the image

Blue-green stone, likely copper-mineral-bearing rock

Uncertain; possibly chrysocolla- or copper-carbonate-bearing material

Rounded gray pebble

Uncertain; likely quartz-rich sandstone, quartzite, or graywacke

Likely iron-rich rock or weathered metallic mineral fragment

Uncertain; possibly limonite/goethite or iron-bearing slag

Likely fluorescent mineral specimen

Uncertain; possibly willemite (Zn₂SiO₄) or fluorite (CaF₂)

Weathered brown rock, likely sandstone

Quartz-rich sandstone (composition uncertain from image)

Polished mixed rock, likely orbicular/epidote-bearing granite or basalt

Uncertain; probable quartz–feldspar–amphibole/epidote aggregate

Weathered rock fragment (likely granite or quartz-rich sandstone)

Uncertain; possible granitic fragment containing quartz and feldspar

Possible tektite or dark volcanic rock fragment

Uncertain; likely natural silicate glass (tektite) or basalt

Tumbled tan pebble, likely sandstone or chert

Uncertain; probable quartz-rich sandstone (SiO₂-bearing)

Likely weathered gray stone or chert fragment

Uncertain; possibly microcrystalline quartz (SiO₂)-rich chert

Possible aquamarine (beryl) crystal fragment

Beryl, Be₃Al₂Si₆O₁₈; green-blue color may indicate aquamarine

Iron-stained chert (possible jasper)

Microcrystalline quartz (SiO₂), likely iron-oxide stained

Vesicular volcanic rock, likely scoria

Scoria; typically basaltic to andesitic composition, chiefly plagioclase, pyroxene, and volcanic glass