Mineral, Specifically A Rock Fragment

Weathered igneous rock fragment, possibly granite or granitic gneiss

Indeterminate; likely quartz–feldspar–mica aggregate (granite), possibly foliated gneiss

Chert Concretion

Chert (Microcrystalline Quartz, SiO2)

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2)

Fossilized Bone Fragment

Vertebrate Fossil Material (Apatite/Calcium Phosphate)

White marble (likely calcitic marble)

Calcite-rich marble; primarily calcium carbonate, CaCO₃

Gravel and Pebbles

Unconsolidated rock fragments / detrital sediment

Moonstone (Green Moonstone / Garnierite)

Potassium Aluminum Silicate (KAlSi3O8) with inclusions of Garnierite

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Fire Opal (in matrix)

Hydrated Silica (SiO2·nH2O)

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica (possibly gneissic if foliation is confirmed)

Breccia

Clastic Breccia (General mineral composition depends on fragments, often SiO2 or CaCO3)

Quartz (Clear/Smoky Geode fragment)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone (with potentially high Feldspar/Arkose content)

Clastic sedimentary rock (SiO2 dominated)

Pink Granite

Felsic intrusive igneous rock (Quartz, K-feldspar, Plagioclase)

Chalcedony (Common Agate)

Cryptocrystalline Quartz (SiO2)

Basalt (with possible alteration or lichen)

Mafic volcanic rock (primarily Plagioclase and Pyroxene)

Likely quartz-rich rock fragment

Probably microcrystalline quartz (SiO₂), possibly a pale chert or quartzite fragment

Moss Agate

Chalcedony (Silicon Dioxide / SiO2)

Sandstone

Arenite (SiO2 primarily)

Greenschist

Greenschist (chlorite-epidote schist)

Fire Opal (Common/Precious in Matrix)

Hydrated Silica (SiO2·nH2O)

Metallic sulfide ore fragment, possibly pyrite-bearing rock

Indeterminate; likely pyrite (FeS₂) in a sulfide-rich matrix

Weathered brown rock fragment

Indeterminate; possibly ferruginous sandstone or weathered volcanic rock

Breciated Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Weathered sandstone fragment

Quartz-rich sandstone, likely arkose or lithic sandstone

Sandstone (Common Quartz Pebble/Rock)

Sedimentary rock / Quartz arenite

Dark, mica-rich metamorphic rock (probable schist or gneiss fragment)

Likely biotite–quartz–feldspar schist; exact identification requires testing

Unidentifiable Specimen

Undetermined

Sandstone (with potential fossil fragments)

Sandstone (SiO2 dominated with iron oxides)

Sandstone

Arenite

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (SiO2 primarily)

Yellow Calcite

Calcium Carbonate (CaCO3)

Sandstone

Clastic Sedimentary Rock

Chert (specifically Tan/Yellow Chert)

Silicon Dioxide (SiO2)

Metallic sulfide mineral fragment, likely galena

Galena (lead sulfide, PbS), tentative identification

Sandstone (with Iron Staining)

Arenite (primarily SiO2 with Fe2O3/FeO(OH) oxides)

Montana Moss Agate

Chalcedony (Silicon Dioxide, SiO2)

Pink Granite

Phaneritic Acidic Igneous Rock (Rich in K-feldspar)

Likely weathered granite or granitic pegmatite fragment

Granite, composed mainly of quartz, feldspar, and dark mica or amphibole

Quartzite (or Chert/Flint gravel)

Quartzite (SiO2 with iron oxide inclusions)