Uncertain

Tumbled brecciated jasper or quartz-rich rock

Brecciated chalcedony/jasper, chiefly microcrystalline SiO₂ with iron-oxide or clay-rich matrix

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chert

Red-orange quartzite or iron-stained quartz

Quartzite; predominantly microcrystalline quartz (SiO₂), with iron-oxide staining

Likely basalt (dark volcanic rock)

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or iron-titanium oxides

Tumbled purple quartz, likely amethyst

Quartz (SiO₂), purple variety commonly colored by iron impurities and irradiation

Green glassy cabochon, likely dyed or synthetic material

Uncertain; possibly green obsidian, chrysoprase, or synthetic glass

Polished dark speckled stone, likely granite or diorite

Granite–diorite granitoid; chiefly quartz, feldspar, and dark mafic minerals

Rounded quartz-rich pebble, likely quartzite or vein quartz

Quartzite (mostly SiO₂), possibly quartz-rich metamorphic rock

Tumbled milky quartz (probable)

Quartz, silicon dioxide (SiO₂)

Quartz-bearing pegmatite

Quartz (SiO₂) with feldspar and mica, likely a granitic pegmatite

Blue glass-like heart pendant, likely synthetic blue spinel or colored glass

Unconfirmed; possibly synthetic spinel (MgAl₂O₄) or cobalt-colored glass

Black obsidian

Volcanic glass; predominantly rhyolitic silica glass (approximately 70–80% SiO₂)

Light-colored carbonate pebble, likely limestone

Limestone; predominantly calcite (CaCO₃), possibly micritic or fossiliferous

Yellow-green tumbled stone, possibly serpentine

Serpentine-group minerals, commonly antigorite or lizardite; composition approximately Mg₃Si₂O₅(OH)₄

Milky quartz (likely iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Tumbled river pebble, likely limestone or weathered chert

Indeterminate carbonate/siliceous pebble; possible micritic limestone or chert

Foliated metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (provisional identification)

Tumbled jasper/quartz-rich pebble

Microcrystalline quartz (SiO₂), likely jasper with iron-oxide inclusions

Blue-gray flint or chert fragment

Microcrystalline quartz (SiO₂), likely flint/chert

Quartz-rich granite or granitic pegmatite fragment

Granite; predominantly quartz (SiO₂), feldspar, and minor mica/iron oxides

Weathered quartz-rich metamorphic rock (likely gneiss or quartzite)

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

Weathered quartz-bearing sandstone or quartzite

Quartzite (SiO₂-rich), possibly weakly metamorphosed sandstone

Serpentinite with green serpentine inclusion

Serpentinite; serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile, with possible magnetite

Tumbled carnelian agate

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide coloration

Quartz-rich metamorphic rock, likely quartzite

Quartzite (mostly microcrystalline quartz, SiO₂)

Likely rose quartz fragment

Quartz, silicon dioxide (SiO₂), pink variety

Iron-rich concretion or ironstone nodule

Likely goethite- and/or hematite-cemented ironstone; exact identification requires testing

Possible yellow calcite fragment

Calcite (CaCO₃), identification uncertain from the image

Likely milky quartz, possibly quartz-rich vein rock

Quartz (SiO₂); identification from the image is uncertain

Small quartz-rich stone, possibly milky quartz or quartz-bearing rock

Quartz (SiO₂), identification uncertain from image

Polished black stone, likely basalt or fine-grained mafic rock

Basalt (probable; identification uncertain from photograph)

Unidentified translucent crystal/mineral fragment

Likely quartz (SiO₂), but visual identification is uncertain

Likely raw metallic sulfide mineral, possibly galena or sphalerite

Uncertain; galena (PbS) or sphalerite (ZnS) are plausible

Likely weathered quartz or feldspar grain

Uncertain; possibly quartz (SiO₂) or a feldspar mineral

Tumbled gray stone, likely quartz-rich pebble

Uncertain; possibly microcrystalline quartz (chalcedony) or quartzite

Likely quartz-rich igneous pebble

Uncertain; possibly granite or quartz-bearing pegmatite

Porphyritic volcanic rock, likely andesite or rhyolite

Porphyritic andesite–rhyolite; chiefly plagioclase, quartz, and altered ferromagnesian minerals in a fine groundmass

Small metallic meteorite fragment (probable stony-iron or iron meteorite)

Unclassified meteoritic material; exact classification requires chemical and petrographic testing

Tumbled green-brown stone, likely serpentine

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite

Massive blue-green rough specimen, likely aquamarine (beryl)

Beryl, Be₃Al₂Si₆O₁₈ (tentative identification)

Rounded quartzite pebble

Quartzite (predominantly recrystallized quartz, SiO₂)

Yellow-orange calcite specimen

Calcite (calcium carbonate, CaCO₃), likely honey or orange calcite