Mineralogical Specimen

Iron-stained quartz-rich rock (likely limonite-bearing quartzite)

Quartzite, predominantly quartz (SiO₂), with iron oxides/hydroxides such as limonite/goethite

Likely weathered basalt

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, with possible olivine and iron oxides

Weathered limestone or calcareous sandstone

Calcite-dominated carbonate rock, likely micritic limestone (CaCO₃)

Agate

Silicon Dioxide (SiO2)

Note: No specimen visible

Porphyritic granite or granitic gneiss

Quartz–feldspar–biotite granite; possibly foliated into granitic gneiss

Tumbled milky quartz (likely iron-stained)

Quartz — silicon dioxide (SiO₂)

Weathered granite (likely granitic river cobble)

Granite; predominantly quartz, feldspar, and mica

Tumbled blue-purple stone, possibly lepidolite or dyed quartz

Tentatively lepidolite (lithium mica; K(Li,Al)₃(Si,Al)₄O₁₀(F,OH)₂), though the photograph is insufficient for confirmation

Chert (with potential fossil inclusion)

Microcrystalline Quartz (SiO2)

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

Granite

Coarse-grained felsic intrusive igneous rock, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende

Quartz pebble or seed/crumb

SiO2 (if quartz)

Echinoidea (Fossil Sea Urchin)

Echinodermata Echinoidea

Tumbled gray stone, likely quartz-rich pebble

Uncertain; possibly microcrystalline quartz (chalcedony) or quartzite

Granite (likely biotite granite)

Coarse-grained felsic plutonic rock composed mainly of quartz, alkali feldspar, plagioclase, and biotite/hornblende

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, possibly altered granite

Quartz-rich sandstone (likely arkosic sandstone)

Sandstone, composed mainly of quartz (SiO₂) with feldspar and minor iron-oxide cement

River Stone (Sedimentary Sandstone/Quartzite)

Arenite/Quartzite transition specimen

Mixed Rock Collection

Polylithic Geological Specimen Mix

Blue-gray kyanite crystal

Kyanite, Al₂SiO₅

Note: Item is not a geological specimen

n/a

Chert

Microcrystalline Quartz (SiO2)

Gold in Quartz Matrix

Native Gold (Au) with Quartz (SiO2)

Gold Ore in Quartz

Auriferous Quartz (Au + SiO2)

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide and dark-mineral inclusions

Botryoidal chalcedony/geode fragment

Microcrystalline quartz (SiO₂), likely quartz-lined cavity with possible calcite

Ferruginous Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Hematite)

Likely quartz-rich rock fragment

Indeterminate; possibly quartz-bearing granite or quartzite

Granite with Mafic Xenolith

Intrusive Igneous Rock containing a Xenolith

Agate Geode

Cryptocrystalline Quartz (SiO2) with Chalcedony banding

Likely iron meteorite fragment

Fe–Ni metallic meteorite, possibly an octahedrite (kamacite–taenite alloy)

Dyed Tumbled Quartz (Dragon's Vein Agate/Quartz)

Silicon Dioxide (SiO2) with artificial dye

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartzite with Hematite staining

Metamorphic Quartzite (SiO2)

Likely a small rough mineral specimen

Unidentifiable from the image; possibly a mica-bearing rock or green mineral

Quartz-rich pegmatite (likely rose/iron-stained quartz)

Quartz, SiO₂, in a coarse granitic pegmatite matrix; possibly with feldspar and mica

Fossilized bivalve shell fragment

Fossil mollusk shell, likely a pectinid or related bivalve; original shell composed mainly of aragonite or calcite, now partly mineralized

Quartz Vein in Schist

Quartz (SiO2) in Mica Schist

Smoky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Malachite specimen

Malachite, Cu₂CO₃(OH)₂, commonly intergrown with chrysocolla and minor copper oxides

Calcite specimen

Calcite (calcium carbonate, CaCO₃), likely pale blue-green massive or cleaved calcite with iron-oxide staining