Organic Gem Material (Botanical)

Weathered conglomeratic volcanic rock

Likely basaltic volcanic breccia or agglomerate, with plagioclase, pyroxene, volcanic glass, and lithic fragments

Unidentified weathered stone, likely quartz-rich metamorphic rock

Possibly quartzite or vein quartz; exact identification is uncertain from the image

Quartzite

Quartzite, composed predominantly of recrystallized quartz (SiO₂)

Tumbled orbicular gabbro (likely oceanic gabbro)

Gabbro; chiefly plagioclase feldspar and pyroxene, with possible olivine, amphibole, and magnetite

Weathered porphyritic volcanic rock (likely andesite or basalt)

Fine-grained intermediate-to-mafic volcanic rock; likely andesite/basalt composed mainly of plagioclase, pyroxene, and possibly altered iron-bearing minerals

Serpentinite-bearing quartz vein rock

Serpentinite (antigorite/lizardite) with milky quartz; possible chlorite or epidote alteration

Iron-rich quartzite or weathered ironstone

Quartzite, chiefly SiO₂, with iron-oxide minerals such as hematite/goethite

Tumbled granite or granitic pebble

Granite; primarily quartz, feldspar, and mica (exact variety uncertain from the image)

Weathered iron-rich rock or concretion

Likely limonite/goethite-bearing concretion; exact identification requires testing

Unidentified rough mineral fragments

Likely quartz- or feldspar-bearing rock; exact identification requires testing

Weathered granite or granitic gneiss boulder

Granite; predominantly quartz, feldspar, and mica (exact identification is uncertain from a photograph)

Weathered granite

Granite; quartz–feldspar–biotite aggregate

Mica-rich quartzite or schist

Quartz–mica metamorphic rock; chiefly SiO₂ with muscovite/biotite mica and minor feldspar

Granitic gneiss (weathered, rounded cobble)

Foliated granitoid; primarily quartz, feldspar, and mica (composition commonly approximates granite)

Olivine in Quartz/Feldspar Matrix (Peridotite or Granitic Pegmatite)

(Mg,Fe)2SiO4 (Olivine) with Quartz / Feldspar

Serpentinized ultramafic rock (serpentinite)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, chromite, talc, and carbonate

Emerald

Beryl, Be₃Al₂(SiO₃)₆, colored green mainly by chromium and/or vanadium

Weathered quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Iron-stained sandstone or weathered ironstone

Ferruginous sandstone; chiefly quartz (SiO₂) cemented or coated by iron oxides such as hematite (Fe₂O₃) and goethite (FeO(OH))

Blue Goldstone

Aventurine Glass

Unakite Jasper / Unakite

Altered Granite (containing Epidote, Orthoclase Feldspar, and Quartz)

Faceted green gemstone, likely peridot

Olivine, gem-quality forsteritic olivine: (Mg,Fe)₂SiO₄

Quartz-bearing feldspar pegmatite (likely with mica/tourmaline)

Granitic pegmatite; chiefly quartz (SiO₂) and feldspar, with dark mica or tourmaline

Emerald in Matrix

Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities

Brown chalcedony/agatic jasper nodule

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony with included or weathered host material

Petrified Wood

Silicified Wood (SiO2)

Tumbled amethyst

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

Weathered calcite-rich limestone fragment

Limestone, predominantly calcite (CaCO₃), possibly bioclastic

Small pale-green stone, possibly serpentine or quartz

Undetermined from the image; no diagnostic features confirm a specific mineral

Black polished stone or mineral fragment

Unidentified opaque dark mineral; possibilities include black tourmaline (schorl), obsidian, or hematite

Yellow chalcedony (likely citrine-like quartz or calcite)

Microcrystalline quartz, SiO₂; alternatively yellow calcite, CaCO₃

Polished iron-stained quartz/quartzite

Quartz (SiO₂), likely quartzite or massive vein quartz with iron-oxide staining

Basaltic Tuff / Volcanic Breccia

Pyroclastic Breccia / Lithic Tuff

Olivine (Peridot)

Magnesium Iron Silicate ((Mg, Fe)2SiO4)

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Sunstone

Oligoclase (a variety of Plagioclase Feldspar) - (Na,Ca)(Si,Al)4O8

Vesicular volcanic rock (likely scoria)

Scoria, typically basaltic to andesitic volcanic rock

Probable weathered sandstone or iron-rich sedimentary rock

Indeterminate siliciclastic rock; likely quartz-rich sandstone with iron-oxide staining

Weathered iron-rich sandstone or ironstone

Ferruginous sandstone; predominantly quartz (SiO₂) cemented or stained by iron oxides/hydroxides

Amphibolite

Hornblende amphibolite; chiefly hornblende and plagioclase feldspar

Weathered metamorphic rock, likely chlorite schist or greenstone

Chlorite-rich schist/greenschist; exact identification requires testing