Mineral (Tectosilicate)

Garnet-bearing quartz (likely almandine garnet in milky quartz)

Quartz (SiO₂) with garnet, likely almandine (Fe₃Al₂(SiO₄)₃)

Merlinite (dendritic opal)

Common opal (hydrated amorphous silica, SiO₂·nH₂O) with dark manganese-oxide dendrites; the trade name “merlinite” is also applied to other patterned stones.

Morganite and Aquamarine (Beryl) Bracelet

Beryllium aluminum silicate, Be3Al2(SiO3)6

Bicolor Quartz Tumble

Silicon Dioxide (SiO2)

Limonite

Hydrated iron oxide-hydroxide, FeO(OH)·nH2O

Weathered granite pebble

Granite, a coarse-grained felsic intrusive igneous rock

Gneiss

Metamorphic Gneiss (High-grade regional metamorphism)

Garden Quartz (Lodalite)

Silicon Dioxide with various mineral inclusions (SiO2)

Limonite Concretion

Limonite (FeO(OH)·nH2O) Pseudomorph

Banded Sandstone (River Cobble)

Arenite Sandstone with heavy mineral layering

Limonite

FeO(OH)·nH2O

Limonite/Goethite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)

Iron Ore (Limonite and Hematite)

Goethite/Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)

Iron-stained banded gneiss

Quartz–feldspar gneiss with iron-oxide staining; exact minerals cannot be confirmed from the image

Limonite (Iron Ore)

Hydrated ferric oxide mixture (FeO(OH)·nH2O)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Polished granite (likely gneissic or migmatitic granite)

Granite, a quartz–feldspar plutonic rock; exact variety cannot be determined from the image

Limonite (Iron Ore / Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Likely greenstone (metamorphosed mafic rock)

Greenschist or altered basalt; exact identification is uncertain from the image

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica, possibly with gneissic foliation

Granite (likely polished or weathered granite)

Granite, a coarse-grained intrusive felsic rock composed mainly of quartz, feldspar, and mica

Small rough mineral grain, possibly olivine (peridot)

Olivine-group silicate, commonly (Mg,Fe)₂SiO₄; identification is uncertain from the image

Small rough mineral or rock fragment (not identifiable from the image)

Undetermined; the specimen is too small and lacks diagnostic visible features for a reliable identification

Unidentified gray mineral/rock fragment

Indeterminate from the photograph; possibly a quartz- or feldspar-bearing rock fragment

Tiny metallic-looking mineral or rock fragment

Unidentifiable from the image; possibly a small metallic mineral grain

Possible green glassy mineral pebble

Undetermined; possibly green aventurine (quartz) or another green mineral

Likely chlorite schist

Chlorite-rich schist; chiefly chlorite with possible quartz and mica

Polished bumblebee jasper bead

Bumblebee jasper (trade name); chiefly calcite, aragonite, and pyrite, with variable realgar/orpiment and other minerals

Likely granitic gneiss pebble

Quartz–feldspar–biotite gneiss (visual identification; exact type uncertain)

Mica Schist / Granite

Mica Schist (Silicate metamorphic rock)

Painted pebble, likely granite or granitic gneiss

Granite (quartz–feldspar–mica rock); exact identification is uncertain from the image

Tumbled granite pebble

Granite, a coarse-grained felsic intrusive igneous rock

Amphibolite

Amphibolite, composed mainly of amphibole and plagioclase feldspar

Polished agate geode slice

Microcrystalline quartz (chalcedony), SiO₂, with possible quartz-lined or calcite-filled cavity

Silver Nuggets (Natural or Cast)

Native Silver (Ag)

Quartz Geode

Silicon Dioxide (SiO2) in Geodic Cavity

Proustite

Proustite (Ag3AsS3)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Cobaltian Calcite

Cobalt-bearing Calcite (Ca,Co)CO3

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Fluorite

Calcium Fluoride (CaF2)