Rock (Likely Sedimentary)

Not a rock, mineral, or geological specimen

Quartz-rich metallic sulfide ore (probable pyrite-bearing rock)

Pyrite, FeS₂, in a quartz-rich host; exact identification is uncertain from the image

Unidentified weathered rock, possibly quartz-bearing granite or rhyolite

Indeterminate; likely quartz–feldspar-rich silicate rock

Grey Basalt or Andesite with Veining

Intermediate to Mafic Extrusive Igneous Rock with Quartz/Calcite Veins

Red Sandstone or Brick Fragment

Arenite (if sandstone)

Basalt Pebble

Basalt

Weathered iron-rich rock, possibly basalt or ironstone

Indeterminate; likely Fe-oxide-bearing basaltic rock (commonly magnetite/hematite in a silicate matrix)

Basalt (with Plagioclase Phenocrysts)

Porphyritic Basalt

Weathered granitic rock fragment

Granite, predominantly quartz–feldspar–mica assemblage

Granite

Granite (Felsic Plutonic Rock)

Weathered quartz-rich sandstone or granitic rock

Indeterminate; likely iron-stained quartz sandstone, possibly weathered granite

Quartz Veined Basalt

Mafic Igneous Rock with Quartz (SiO2) intrusion

Native copper-bearing rock (probable copper ore)

Native copper (Cu), likely with copper sulfide/oxide minerals in a host rock

Mica-rich metamorphic rock, likely schist

Biotite–muscovite schist, possibly garnet-bearing

Granite (Weathered)

Granitic intrusive rock

River Cobble (Basaltic/Andesitic)

Mafic Igneous Porphyritic Rock

Weathered gray sandstone or siltstone

Clastic siliciclastic rock, primarily quartz and feldspar grains cemented by silica or carbonate

Granite (Weathered)

Felsic Plutonic Rock (primarily Quartz, Feldspar, and Mica)

Diorite with Xenolith

Phaneritic Intermediate Plutonic Rock

Painted River Rock (likely Quartzite or Granite)

Quartzite or Granitic Gneiss (painted)

Likely weathered iron-rich rock

Probable basalt or limonite/goethite-stained mafic rock; exact identification requires testing

River Stone (likely Siltstone or fine-grained Basalt)

Clastic Sedimentary (Siltstone) or Mafic Igneous (Basalt)

Banded metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification requires a fresh surface and mineral tests

Dark gray volcanic rock, probably andesite or basalt

Fine-grained mafic–intermediate volcanic rock; likely basalt (plagioclase ± pyroxene), possibly andesite

Sandstone (Pebble/Conglomerate fragment)

Sandstone (clastic sedimentary rock)

Mixed tumbled stone collection

Assorted minerals, likely including quartz, jasper, agate, and possibly obsidian or hematite

Gneiss (likely)

Gneiss

Granite Pebble

Felsic Intrusive Igneous Rock

Shale

Fissile Mudstone (primarily composed of phyllosilicate minerals like kaolinite, montmorillonite, and illite)

Dalmatian Jasper

Peralkaline rock with Tourmaline spots

Serpentine (likely serpentinized ultramafic rock)

Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; commonly derived from peridotite

Iron sulfide-rich ore, possibly pyrite-bearing gossan

Likely pyrite (FeS₂) with iron oxides/hydroxides and host rock; exact identification requires testing

Magnetite or Ironstone Nodule

Magnetite (Fe3O4) or Hematite-rich Sedimentary Nodule

Granite or Porphyritic Igneous Rock (weathered)

Granitoid

Jasper with Hematite Inclusions

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3)

Likely basaltic volcanic rock

Basalt, chiefly plagioclase feldspar and clinopyroxene, with possible olivine or iron oxides

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

River Stone (likely Basalt or Diabase)

Mafic Igneous Rock (likely Basalt)

Quartz Pebble

Silicon Dioxide (SiO2)

Weathered granitic rock fragment

Likely granite or granodiorite, composed mainly of quartz, feldspar, and mica

Chalcedony (Agate/Jasper mix in host rock)

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Banded Gneiss (River Cobble)

Gneiss (a high-grade metamorphic rock)