Anthropogenic Material

Banded chert or agate

Microcrystalline quartz (chalcedony), SiO₂

Tumbled greenstone or serpentine pebble

Likely serpentinite, composed mainly of serpentine-group minerals (antigorite/lizardite); identification is uncertain from the image alone

Rounded brown pebble, likely chert or iron-stained quartzite

Microcrystalline quartz (SiO₂), possibly quartzite; identification is uncertain from the image

Green aventurine (likely)

Quartzite composed mainly of quartz (SiO₂), colored by fuchsite or other chromium-bearing mica

Tumbled yellow jasper or silicified rock fragment

Microcrystalline quartz (chalcedony), SiO₂, likely iron-oxide colored

Tumbled brown jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly with chalcedony and iron oxides

Weathered iron-rich rock, possibly jasper or ironstone

Likely limonite/goethite-bearing siliceous rock; exact identification requires hardness and streak tests

Polished Mexican “Crazy Lace” agate tower

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide inclusions

Red-orange sunstone (likely aventurine feldspar) bead bracelet

Feldspar, commonly oligoclase or labradorite with copper inclusions; composition varies by source

Rhyolitic jasper or iron-stained chert

Microcrystalline quartz (SiO₂), likely with hematite/goethite staining

Polished ocean jasper (orbicular jasper)

Microcrystalline quartz/chalcedony with iron- and manganese-bearing inclusions; SiO₂

Petrified Wood

Silicified Wood (primarily SiO2)

Moss agate (likely plume or dendritic agate)

Chalcedony, microcrystalline quartz (SiO₂), with iron-oxide inclusions

Diamond (or Simulant)

Carbon (C) or relevant simulant formula (e.g., ZrO2 for Cubic Zirconia)

Carved labradorite fish

Labradorite, calcium-rich plagioclase feldspar (approximately (Ca,Na)(Al,Si)₄O₈)

Likely sodalite

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Quartz vein material, likely milky quartz with iron staining

Quartz (SiO₂), possibly with feldspar and iron-oxide staining

Colorless faceted gemstone, likely quartz

Quartz (SiO₂), probably rock crystal; exact identification is uncertain from the strongly backlit image

Fossilized shell fragment

Likely calcitic or aragonitic bivalve/gastropod shell; exact taxon indeterminate

Greenstone (likely serpentine-rich rock)

Serpentinite, composed mainly of serpentine-group minerals

Milky quartz

Quartz (silicon dioxide, SiO₂)

Polished basalt pebble

Basalt, a fine-grained mafic volcanic rock; chiefly plagioclase, pyroxene, and iron-titanium oxides

Red Sandstone

Arenite (SiO2 with Fe2O3)

Weathered gray stone, possibly basalt or granitic rock

Indeterminate fine- to medium-grained silicate rock; possible basalt, diabase, or weathered granite

Likely reddish-brown chert or jasper fragment

Microcrystalline quartz (SiO₂), possibly iron-oxide-bearing jasper

Vesicular volcanic rock, likely weathered scoria

Scoria (vesicular basaltic-andesitic volcanic rock), composition approximately plagioclase, pyroxene, and volcanic glass

Tumbled milky quartz

Quartz, silicon dioxide (SiO₂)

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

Sandstone

Arenite (composed primarily of SiO2)

Limestone

Calcium Carbonate (CaCO3)

Chert (or Flint)

Microcrystalline Quartz (SiO2)

Quartzite

Quartzite (primarily SiO2)

Limestone

Limestone (Calcium Carbonate, CaCO3)

Engraved purple stone cabochon, possibly amethyst

Unconfirmed; if amethyst, quartz (SiO₂)

Serpentine (often sold as “new jade”), polished egg

Serpentinite, composed chiefly of serpentine-group minerals (approx. Mg₃Si₂O₅(OH)₄); dark patches may be magnetite or other accessory minerals

Diamond

C (Carbon)

Tumbled dark stone, likely basalt or gabbro

Basalt (fine-grained mafic rock), possibly gabbro; mainly plagioclase and pyroxene

Tumbled pegmatitic rock, likely amazonite-bearing granite

Granite/pegmatite composed mainly of quartz, feldspar, and mica; blue-green area may be microcline (amazonite)

Vesicular volcanic rock, likely weathered pumice or scoria

Pumice/scoria; predominantly volcanic glass and feldspar, with possible iron oxides

Jasper

Silicon Dioxide (SiO2)

Chrysocolla-bearing copper ore

Chrysocolla (hydrated copper aluminosilicate), commonly with malachite, azurite, quartz, and limonite

Chert (Flint)

Microcrystalline Quartz (SiO2)