Mineralogical Specimen

Greenstone pebble

Likely chlorite- or epidote-bearing metamafic rock (metabasalt/greenschist)

Fossilized shell fragment

Bioclastic carbonate, likely a bivalve or brachiopod shell preserved as calcite/aragonite

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially granitic or quartzitic material

Chert (Green River Chert)

Microcrystalline Quartz (SiO2)

Veined dark metamorphic rock, likely serpentinite

Serpentinite, predominantly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible quartz, calcite, and magnetite veins

Likely serpentine-rich ultramafic rock

Serpentinite; chiefly serpentine-group minerals (Mg3Si2O5(OH)4), commonly with magnetite and relict olivine/pyroxene

Granite-like rock

Felsic intrusive igneous rock, probably granitic or granodioritic

Rounded graywacke or sandstone cobble

Lithified clastic sandstone; likely quartz–feldspar–lithic grain aggregate in a silica or calcite matrix

Mica-rich metamorphic rock, likely schist

Muscovite–biotite schist, possibly with quartz and feldspar

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica/amphibole

Likely graphite-rich schist

Graphitic schist; chiefly graphite and quartz/mica

Brown agate or chalcedony cabochon pendant

Microcrystalline quartz (SiO₂), likely brown chalcedony/agate

Greenish weathered volcanic rock, likely altered basalt

Altered basalt/mafic volcanic rock; green coloration may reflect chlorite, epidote, or celadonite

Dark metamorphic rock, likely biotite schist or hornblende-bearing gneiss

Probable mica schist/amphibolite; composition may include biotite, amphibole, quartz, feldspar, and iron oxides

Iron-stained metamorphic rock, likely quartzite or jasper

Quartz-rich rock dominated by SiO₂, with iron oxides/hydroxides (hematite, goethite) and possible clay or mica

Weathered iron-rich concretion or breccia

Goethite/hematite-bearing limonite concretion, possibly ferruginous sandstone

Gold-bearing pyrite-rich rock (iron pyrite)

Pyrite, FeS₂, likely in a quartz- or sulfide-rich matrix

Rhodonite-bearing metamorphic rock

Manganese-rich metamorphic rock, chiefly rhodonite (MnSiO₃), with quartz and manganese oxides

Polished orbicular granite (likely K2-type granite)

Granite, chiefly quartz, alkali feldspar, plagioclase, and dark amphibole/biotite; possible epidote-rich orbicules

Iron-rich weathered stone, possibly hematite-rich ironstone

Hematite/goethite-bearing ironstone; predominantly Fe₂O₃ and FeO(OH)

Weathered quartz-rich rock, likely quartzite or milky-quartz vein material

Quartzite (dominantly SiO₂), possibly quartz-vein breccia with iron-oxide staining

Iron-stained quartz-rich rock, likely pegmatite or quartz vein fragment

Quartz (SiO₂) with feldspar, mica, and iron-oxide/hydroxide staining; possibly weathered granite pegmatite

Iron-rich weathered rock, possibly limonite/goethite-bearing ore

Limonite (hydrated iron oxides; chiefly goethite, FeO(OH), with hematite and other oxides possible)

Small rounded pebble, likely limestone or quartz-rich sedimentary fragment

Indeterminate lithic clast; probable micritic limestone (CaCO₃) or weathered quartz-rich stone

Weathered mineralized rock fragment

Indeterminate; likely quartz–feldspar-rich lithic material with iron-oxide staining

Tumbled serpentinite (likely)

Serpentinite; chiefly antigorite/lizardite/chrysotile, Mg3Si2O5(OH)4, with accessory magnetite and possibly chromite

Dark mafic rock, likely basalt with iron-oxide veining

Basalt; predominantly plagioclase and pyroxene, possibly olivine, with hematite/goethite staining

Mica Schist (with Golden/Biotite inclusions)

K(Mg,Fe)3AlSi3O10(F,OH)2 (Biotite), KAl2(AlSi3O10)(F,OH)2 (Muscovite)

Greenstone (likely altered basalt or greenschist)

Greenschist-facies mafic rock; commonly chlorite–actinolite–albite ± epidote, or chlorite-altered basalt

Tumbled quartz-rich pebble

Quartz (SiO₂), possibly iron-stained milky quartz or quartzite

Weathered sandstone or siltstone

Clastic sedimentary rock, chiefly quartz and feldspar grains cemented by silica, iron oxides, or carbonate

Polished green serpentine

Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄

Prasiolite and Quartz Crystal Cluster

Quartz (SiO2); Prasiolite is a variety of Quartz

Orbicular basalt (amygdaloidal basalt)

Basalt, commonly with iron-oxide–stained amygdules; matrix chiefly plagioclase, pyroxene, and often olivine

Dark slate or fine-grained metamorphic rock

Slate; chiefly fine-grained phyllosilicates, quartz, and feldspar

Sapphire

Corundum (Al2O3)

Fossilized bivalve shell

Bivalvia indeterminate; likely a preserved clam or cockle shell, composed mainly of calcium carbonate (CaCO₃)

Pyrite-bearing quartz or sulfide-rich rock

Pyrite (FeS₂) in quartz-rich matrix, possibly with chalcopyrite

Granite (Dioritic or Hornblende-rich)

Phaneritic Plutonic Felsic to Intermediate Igneous Rock

Greenstone (probable altered basalt)

Chlorite–epidote–actinolite-rich greenschist; composition commonly derived from basalt

Small brown rock fragment

Undetermined; possibly weathered iron-stained quartzite or chert

Likely basalt pebble

Basalt, a fine-grained mafic volcanic rock; commonly composed of plagioclase, pyroxene, and sometimes olivine