Mineral, Possibly Rock Fragment Containing A Mineral

Lichen-covered graywacke or granitic glacial cobble

Indeterminate; likely quartz–feldspar–mica rock, possibly weathered granite or granodiorite

Weathered iron-rich rock, possibly basalt or ironstone

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

Dark volcanic rock, likely basalt

Basalt; fine-grained mafic silicate rock dominated by plagioclase and pyroxene, commonly with olivine

Tumbled quartz-rich rock, possibly jasperized quartz or quartzite

Quartz (SiO₂), likely with iron-oxide staining and minor feldspar or other silicate minerals; exact identification is uncertain from the photograph

Amethyst cluster

Amethyst, purple quartz (SiO₂)

Red Sandstone with Reduction Spot

Quartzose Sandstone with a Leach/Reduction Spot

Unidentified rock fragments

Indeterminate; likely a weathered, iron-stained silicate rock

Dark gray fine-grained rock, likely basalt

Basalt; chiefly plagioclase feldspar and pyroxene, often with minor olivine and magnetite

Likely petrified wood or silicified fossil fragment

Silicified wood; predominantly microcrystalline quartz (SiO₂)

Quartz (milky quartz), possibly calcite

Quartz: SiO₂; visual identification is uncertain because the specimen is wet and lacks diagnostic crystal faces

Metallic sulfide mineral specimen, likely pyrite

Pyrite (FeS₂), possibly a pyrite-rich sulfide aggregate

Gabbroic rock, possibly hornblende gabbro

Gabbro; coarse-grained mafic silicate rock dominated by plagioclase and pyroxene, with possible hornblende and magnetite

Chert (Banded)

Cryptocrystalline Silica (SiO2)

Amygdaloidal Basalt with Secondary Minerals

Basalt containing secondary mineralization (likely Chlorite, Celadonite, or Zeolites)

Brecciated stone pebble

Breccia

Likely polished basalt with pale mineral inclusions

Basalt; inclusions possibly calcite, quartz, or weathered feldspar

Shale (possibly)

Shale (fine-grained clastic sedimentary rock)

Fossilized Bone Chunk

Permineralized Vertebrate Bone (indeterminant)

Honey calcite (calcite-rich limestone/marble fragment)

Calcite — CaCO₃; likely coarse crystalline calcitic rock

Likely weathered quartz-bearing rock (uncertain identification)

Possibly quartz-rich granite or granitic aplite; exact identification requires a clearer, larger image and tests

Likely weathered quartz-rich stone or fossil fragment

Indeterminate; possibly quartz-bearing sandstone, iron-stained quartz, or a fragmentary fossil

Quartz-rich pegmatitic rock, possibly rose quartz with mica

Granitic pegmatite; predominantly quartz (SiO₂), with feldspar and mica

Vesicular basalt (likely weathered lava rock)

Basalt; fine-grained mafic volcanic rock composed chiefly of plagioclase, pyroxene, and commonly olivine

Breccia

Breccia (Sedimentary Clastic Rock)

Generic Rock Fragment

Rock Fragment

Weathered quartz-rich rock, likely granite or granitic gneiss

Granite (quartz–feldspar–mica aggregate), possibly weathered granitic gneiss

Weathered metallic sulfide-bearing rock, possibly chalcopyrite ore

Likely chalcopyrite (CuFeS₂) in a weathered host rock; identification is uncertain from the photograph

Fossiliferous Rock (Invertebrate Fossil in Matrix)

Fossiliferous limestone or shaly matrix containing skeletal fossil remains

Generic Pebble

Lithic Fragment

Quartz-rich river pebble, likely milky quartz

Milky quartz (SiO₂), possibly a quartzite or quartz-rich silicate pebble

Greywacke (likely)

Greywacke (a type of sandstone)

Light-colored limestone (probable fossiliferous or micritic limestone)

Calcite-rich carbonate rock; predominantly CaCO₃ (calcite)

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Weathered carbonate rock, possibly fossiliferous limestone

Calcite-rich limestone (CaCO₃), tentative identification

Polished black mineral or volcanic glass fragment

Indeterminate; possibly obsidian or black tourmaline

Tumbled dark pebble

Indeterminate; likely basalt or fine-grained dark metamorphic rock

Tumbled epidote or epidote-rich stone

Epidote, Ca₂(Al,Fe)₃(SiO₄)₃(OH); possibly a green jasper or prehnite-epidote aggregate

Sandstone (likely Ferruginous)

Sandstone (SiO2 with iron oxides)

Likely basalt or scoria fragment

Dark mafic volcanic rock, most likely basalt (plagioclase–pyroxene–olivine) or vesicular scoria

Sandstone (likely Graywacke or Lithic Arenite)

Clastic sedimentary rock predominantly composed of silicate grains

Amethyst geode fragment

Quartz, SiO₂; purple color from irradiation-related iron impurities

Concrete

Anthropogenic Conglomerate