Industrial Byproduct

Coal (Bituminous / Anthracite)

Carbonaceous Sedimentary Rock (C)

Garnet-bearing schist

Mica schist with garnet porphyroblasts; garnet likely almandine, Fe₃Al₂(SiO₄)₃

Weathered yellow-brown rock pebble

Undetermined; possibly iron-oxide-stained sandstone or mudstone

Milky quartz

Quartz, silicon dioxide (SiO₂)

Small blue-green mineral or stone bead

Unidentified opaque blue-green mineral; the image is insufficient for reliable species identification

Red gemstone ring, possibly synthetic ruby or red glass

Unidentified red stone; ruby is corundum (Al₂O₃), but the image cannot confirm its identity

Ruby ring (likely synthetic ruby)

Corundum, Al₂O₃; red color from chromium. The image alone cannot establish whether the stone is natural or lab-grown.

Rock specimen shown in a classroom identification activity

Undetermined; the pictured specimen may be a fine-grained, pinkish rock, but the image does not provide enough detail for a reliable identification

Tumbled brecciated jasper (likely)

Jasper, an opaque microcrystalline variety of quartz (SiO₂), with pale quartz/chalcedony veins

Red faceted gemstone, likely synthetic ruby

Corundum (Al₂O₃); ruby is red chromium-bearing corundum

Rounded pebble, likely quartz-rich river or beach pebble

Unidentified lithic clast; possibly quartzite or iron-stained quartz-rich rock

Ruby ring

Corundum (Al₂O₃), red variety colored mainly by chromium

Rounded tan pebble

Unidentified fine-grained rock; the image does not show enough detail for a reliable species-level identification.

Polished calcite sphere

Calcite (CaCO₃), likely banded or massive calcite

Small rounded pebble, likely quartz-rich river or beach stone

Unidentified lithic pebble; exact rock type cannot be determined from the image

Possible iron-rich pebble with a weathered inclusion

Unidentified; image alone does not support a reliable mineral or rock identification

Blue-gray stone pebble (possibly slag or a weathered rock)

Unidentified fine-grained rock; composition cannot be determined from the image

Calcite

Calcium carbonate (CaCO3)

Likely weathered quartz-bearing rock

Uncertain; possibly quartz-rich feldspathic material, with iron-oxide staining

Fossil brachiopod shell

Likely a ribbed orthid or productid brachiopod; exact genus cannot be determined from this image

Fossil shark tooth

Likely a fossilized shark tooth, possibly Carcharhinus or a related requiem shark; exact species is indeterminate from the image.

Milky Quartz Boulder

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Diamond

Carbon (C)

Quartzite pebble

Metamorphic Quartzite (SiO2)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Agate

Chalcedony (SiO2)

Diamond (set in a eternity ring band)

Carbon (C)

Sandstone (lithic/quartz variant)

Clastic sedimentary rock (SiO2 predominant)

Small weathered fossil or mineral fragment

Indeterminate; possibly fossilized shell, bone, or a pale carbonate mineral

Likely fossilized shark tooth

Possibly *Carcharocles* or *Otodus* sp.; exact identification requires scale and detail

Peridot in Matrix

Olivine ((Mg,Fe)2SiO4)

Quartz in Matrix

Silicon Dioxide (SiO2) in host rock matrix

Yellow Calcite

Calcium Carbonate (CaCO3)

Sandstone

Arenite (SiO2 principal)

Kimberlite with Diamonds

Kimberlite (ultramafic potassic igneous rock)

Quartzite Pebble

Quartzite (SiO2)

Quartz (Iron-Stained)

Crystalline Silicon Dioxide (SiO2)

Quartz (Agate/Chalcedony)

Silicon Dioxide (SiO2)

Chalcedony Pebble

Cryptocrystalline Quartz (SiO2)

Chert (Iron-Stained)

Chert (Silicon Dioxide, SiO2)

Red Garnet (likely Almandine)

Almandine (Fe3Al2(SiO4)3)