Mineralogical

Rounded river pebble, likely quartz-rich sandstone or weathered quartzite

Indeterminate; probable quartz (SiO₂)-rich clastic rock

Greenstone pebble

Likely chlorite- or epidote-bearing metamafic rock (metabasalt/greenschist)

Probable weathered basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly plagioclase ± pyroxene, amphibole, and iron oxides

Granite

Felsic intrusive igneous rock

Weathered porphyritic volcanic rock

Likely andesite or dacite, with feldspar phenocrysts in a fine-grained groundmass

Sandstone (Quartzose Sandstone)

Arenite (primarily SiO2 with minor Fe2O3)

Weathered greenstone / serpentinite (probable)

Serpentinite, chiefly antigorite–lizardite Mg₃Si₂O₅(OH)₄; possibly altered mafic greenstone

Malachite-bearing copper ore

Malachite (Cu₂CO₃(OH)₂), likely mixed with chrysocolla, limonite, or native copper minerals

Quartz-bearing dark mineral specimen

Quartz (SiO₂) on a dark host rock, possibly basalt or sulfide-rich ore

Serpentine-rich metamorphic rock

Serpentinite; chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄, possibly with talc, chlorite, magnetite, or carbonate

Weathered, iron-stained feldspathic rock (probable granite or granitic pegmatite)

Quartz–feldspar granitoid; visible blue grains may be altered feldspar or accessory minerals

Jasper and Greenstone Pebble

Siliceous rock / Metamorphic pebble

Rounded iron-rich pebble

Likely ferruginous sandstone or ironstone; exact identification requires testing

Quartzite

Quartzite (SiO2)

Polished porphyritic volcanic rock, likely andesite or basalt

Porphyritic andesite/basalt; commonly plagioclase and pyroxene phenocrysts in a fine volcanic groundmass

Black volcanic rock, likely basalt

Basalt; primarily plagioclase feldspar and pyroxene, commonly with minor olivine or magnetite

Greenish weathered volcanic rock, likely altered basalt

Altered basalt/mafic volcanic rock; green coloration may reflect chlorite, epidote, or celadonite

Likely weathered basalt pebble

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

Granite

Intrusive igneous rock composed mainly of quartz, alkali feldspar, and plagioclase

Gneiss (specifically a granitic gneiss cobble)

Gneiss (high-grade regional metamorphic rock)

Weathered green metamorphic rock, possibly serpentinite or greenstone

Likely serpentinite (serpentine-group minerals) or chlorite/epidote-rich greenschist; exact identification requires testing

Dark gray fine-grained stone, likely basalt

Basalt; primarily plagioclase feldspar and pyroxene, commonly with minor olivine and iron oxides

Weathered metal-rich igneous rock, likely basalt or komatiitic peridotite

Probable altered mafic–ultramafic rock containing pyroxene/amphibole, olivine, iron oxides, and possible metallic sulfides

Mica-rich pegmatitic granite

Granitic pegmatite, chiefly quartz, feldspar, and muscovite/biotite mica

Serpentine-bearing metamorphic rock (likely chromite/vesuvianite-bearing serpentinite)

Serpentinite, chiefly serpentine-group minerals [(Mg,Fe)₃Si₂O₅(OH)₄], with dark accessory minerals

Serpentinized ultramafic rock with magnesite

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with likely magnesite (MgCO₃) and minor chromite/magnetite

Quartzite

Quartzite (primarily SiO2)

Quartz-veined metamorphic rock, likely quartzite or schist

Quartz-rich metamorphic rock with a milky-quartz vein; exact host rock is indeterminate from the photo

Granite-like pegmatitic rock

Coarse-grained granite or granitic pegmatite; likely quartz–feldspar–mica aggregate

Serpentinite with carbonate veins and weathering rind

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), with calcite/magnesite and accessory magnetite

Weathered gray-green basaltic rock

Basalt, likely altered to low-grade greenschist/amphibolite facies

Greenstone / altered basalt (probable)

Chlorite–epidote–actinolite aggregate; commonly metabasalt (greenstone)

Iron-rich breccia or weathered ironstone

Goethite–hematite-bearing ferruginous rock, possibly limonite

Serpentine-rich metamorphic rock

Serpentinite, likely with quartz or calcite veining and minor magnetite

Quartz-bearing rock, possibly weathered granite or pegmatite

Quartz–feldspar–mica aggregate; exact classification is uncertain from the image

Quartz-rich pegmatite (weathered feldspar–quartz rock)

Granitic pegmatite; primarily quartz (SiO₂), feldspar, and minor biotite/iron-oxide minerals

Uncertain polymict breccia or altered volcanic rock

Likely hydrothermally altered volcanic breccia; exact mineral identification requires testing

Mica Schist

Mica Schist (primarily Muscovite or Biotite)

Polished septarian nodule

Septarian concretion, commonly calcite/aragonite with brown iron-oxide or siderite veins in a clay-rich matrix

Quartz-bearing weathered rock

Massive to drusy quartz (SiO₂), possibly in a feldspathic or carbonate host

Altered volcanic rock, possibly andesite

Likely porphyritic andesite or dacite with secondary chlorite/epidote and quartz–calcite veins

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)