Mineral, Possibly Rock Fragment Containing A Mineral

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

Quartz (Druzy/Macro-crystalline)

Silicon Dioxide (SiO2)

Quartzite Geode (unopened)

SiO2 (Silicon Dioxide)

Garnet-bearing metamorphic rock, possibly garnet amphibolite or mica schist

Almandine garnet (Fe₃Al₂Si₃O₁₂) in a mafic, amphibole–feldspar-rich matrix

Banded calcite (likely marble or calcite-rich limestone)

Calcite, CaCO₃; possibly calcitic marble

Basalt

Mafic Igneous Rock (composed primarily of pyroxene and calcium-rich plagioclase)

Biotite (Black Mica)

Biotite [K(Mg,Fe)3(AlSi3O10)(F,OH)2]

Pegmatitic mica-quartz-feldspar specimen

Granitic pegmatite, chiefly quartz (SiO₂), feldspar, and muscovite/biotite mica

Orbicular Granite

Orbicular Granidiorite / Plutonic Igneous Rock

Fuchsite

Chromium-bearing Muscovite - K(Al,Cr)2(AlSi3O10)(OH)2

Amber (Copal)

Succinite (fossilized resin)

Fossilized Bone Fragment

Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)

Quartz fragment (Pebble)

Silicon Dioxide (SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Granite Pebble

Granite

Weathered quartz-rich rock, possibly chert or quartzite fragment

Indeterminate; likely microcrystalline quartz (SiO₂), possibly with iron-oxide staining

Black granite (likely polished gabbro or diabase)

Granitoid rock dominated by feldspar, quartz, and dark mafic minerals; exact identification requires testing

Quartz / Common Opal

Silicon Dioxide (SiO2)

Basalt with Vesicle/Vug

Basalt (Aphanitic Mafic Igneous Rock)

Turquoise

Hydrated copper and aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O)

Unknown Organic Object (likely a berry or fruit)

Not applicable; this is not a geological specimen. If it were a cranberry, its scientific name would be Vaccinium macrocarpon; if a cherry, it would be Prunus avium or Prunus cerasus.

Weathered iron-rich rock, possibly limonite-bearing sandstone or laterite

Limonite/goethite-rich ferruginous rock; exact identification requires testing

Sandstone Geode (Unbroken)

Siliciclastic sedimentary rock (primarily Quartz)

Small rounded pebble, likely quartz-rich river stone

Indeterminate; likely quartz/chert-bearing lithic clast

Chalcedony Geode Fragment

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hydrothermal Quartz Breccia

Hydrothermal Breccia with Quartz and Chloritic/Epidote Clasts

Granite or granitic rock fragment

Coarse-grained felsic intrusive rock, chiefly quartz, feldspar, and mica/amphibole

Granite (Pebble)

Granite (composed of Quartz, Feldspar, and Mica/Amphibole)

Druzy quartz geode

Microcrystalline quartz (SiO₂), commonly lining a volcanic geode cavity

Pegmatite with Tourmaline and Quartz

Igneous Pegmatite

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with marine fossils

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Vesicular Basalt

Aphanitic Mafic Igneous Rock (with vesicles)

Obsidian

Volcanic Glass

Iron-stained quartz-rich rock, possibly gold-bearing quartz

Quartz (SiO₂) with iron-oxide staining; possible limonite/goethite matrix

Sandstone

Sedimentary Rock (Quartz arenite/Arkose)

Laterite (iron-rich nodule, possibly Bauxite as a subtype)

Laterite (composed of various minerals including goethite, hematite, gibbsite, etc.)

Greenstone / altered mafic rock

Likely chlorite–actinolite schist or metabasalt; exact identification requires testing

Weathered quartz-bearing rock, possibly granite or gneiss

Indeterminate; likely quartz–feldspar–mica aggregate, possibly granitic gneiss

Quartz Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Agate (or Banded Agate)

Agate (a variety of Chalcedony, which is a cryptocrystalline form of Quartz); Chemical Formula: SiO₂ (Silicon Dioxide)

Porphyry (Rhyolite / Andesite Porphyry Pebble)

Porphyritic Igneous Rock