Basalt

Vesicular basalt

Basalt, likely amygdaloidal or scoriaceous basalt

Weathered basaltic rock

Basalt, likely amygdaloidal or altered basalt

Weathered basaltic volcanic rock

Basalt, likely vesicular/amygdaloidal basalt

Weathered basaltic cobble

Basalt, likely amygdaloidal or vesicular basalt

Small dark rock fragment (likely basalt or slag)

Tentatively basalt; exact identification is uncertain from the photograph

Basalt

Mafic Volcanic Rock (composed of Plagioclase Feldspar and Pyroxene)

Dark fine-grained pebble, possibly basalt

Basalt (tentative identification)

Weathered basaltic rock

Basalt, likely vesicular or altered basalt

Likely basaltic rock with vesicles

Vesicular basalt, possibly amygdaloidal basalt

Vesicular Basalt (Iron-rich)

Scoriaceous Basalt / Oxidized Vesicular Basalt

Likely basalt fragments

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

Vesicular basalt (possibly scoriaceous basalt)

Basalt; primarily plagioclase, clinopyroxene, olivine, and iron-titanium oxides

Basalt

Basalt (Aphanitic Mafic Volcanic Rock)

Basalt Pebble

Mafic Igneous Rock (Basalt)

Crushed basalt and andesite aggregate

Basalt–andesite volcanic rock; primarily plagioclase feldspar, pyroxene, and minor olivine or amphibole

Gabbro (River Cobble)

Phaneritic Mafic Igneous Rock

Basalt

Basalt (Mafic volcanic rock)

Gabbro

Gabbro

Basalt

Aphanitic Mafic Igneous Rock

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Likely basalt (dark mafic rock)

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Basalt

Basalt (dominated by plagioclase feldspar, pyroxene, and olivine)

Weathered basalt or mafic volcanic rock

Basalt; primarily plagioclase feldspar, pyroxene, and possibly olivine

Gabbro

Plutonic mafic rock

Basalt

Mafic volcanic rock (primarily plagioclase feldspar and pyroxene)

Dark basalt cobble

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

Basalt

Extrusive igneous rock

Dark mafic rock, likely basalt

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine

Dark igneous rock, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and possibly olivine

Small dark rock, possibly basalt or a weathered pebble

Unidentified specimen; basalt is a possible visual match, but the image lacks diagnostic detail

Weathered basaltic rock (probable basalt or scoria)

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or volcanic glass

Likely weathered basaltic rock or slag-like volcanic specimen

Fine-grained mafic rock, probably basalt; exact identification requires testing

Basalt

Extrusive Igneous Rock

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Possible slag or basalt fragment

Indeterminate dark mafic material; likely basalt (plagioclase–pyroxene) or industrial iron-rich slag

Weathered mafic igneous rock, likely basalt

Basalt (fine-grained mafic volcanic rock; exact identification is uncertain from the image)

Dark, fine-grained pebble (likely basalt)

Basalt; exact identification requires closer examination

Dark gray-green, fine-grained rock (likely basalt)

Basalt; exact identification requires closer examination

Basalt

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

Basalt

Basalt (containing Pyroxene, Plagioclase Feldspar, and Olivine)

Basalt

Basalt (Aphanitic Mafic Volcanic Rock)

Basalt

Extrusive Igneous Rock