Not A Geological Specimen

Banded iron formation fragment

Banded iron formation (BIF), chiefly hematite/magnetite and chert (SiO₂)

Weathered gray sandstone or fine-grained metamorphic rock

Likely quartz-rich sandstone (quartz arenite), possibly weakly metamorphosed metasandstone

Concrete-like limestone or cemented carbonate rock

Likely limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image

Weathered fossiliferous limestone

Calcitic limestone, predominantly calcium carbonate (CaCO₃), possibly bioclastic limestone

Tumbled dark mineral on a polished brown stone slab

Likely quartz-rich chalcedony or jasper slab with a dark metallic mineral inclusion; exact identification is uncertain from the photograph

Unidentified small mineral fragment

Possibly quartz or feldspar-bearing rock; exact identification is uncertain from the image

Faceted gemstone pendant, likely quartz or citrine

Indeterminate from photograph; likely quartz (SiO₂), possibly yellow citrine or treated quartz

Assorted gemstone jewelry

Mixed natural and synthetic gemstone cabochons and faceted stones; individual species cannot be determined reliably from this image

Tumbled aqua glassy mineral specimen, likely chrysocolla or turquoise imitation

Uncertain from image; possible chrysocolla (hydrated copper aluminosilicate, variable composition) or dyed/man-made glass

Peridot gemstone pendant

Olivine, gem-quality forsteritic olivine (approximately (Mg,Fe)₂SiO₄)

Mixed rock and mineral specimen collection

Multiple species, likely quartz (SiO₂), calcite (CaCO₃), feldspar, chert, and assorted volcanic/sedimentary rocks

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

Fossiliferous limestone

Bioclastic calcarenite/calcirudite, chiefly calcium carbonate (CaCO₃)

Weathered lateritic ironstone / ferruginous rock

Goethite–hematite-rich laterite, commonly with quartz and clay minerals

Iron-rich weathered rock, possibly limonite-bearing sandstone or laterite

Goethite–hematite/limonite assemblage, likely in a ferruginous sandstone or weathered host rock

Rounded dark gray cobble

Likely basalt or fine-grained mafic volcanic rock; exact identification requires testing

Light-colored chert or weathered limestone

Microcrystalline quartz (SiO₂) or calcitic limestone (CaCO₃); exact identification requires testing

Pale granite pebble (tentative identification)

Granite; a coarse-grained felsic intrusive igneous rock composed primarily of quartz and feldspar, with minor mica or amphibole

Faceted glass-like gemstone object

Likely synthetic glass or cubic zirconia; exact material cannot be confirmed from the image

Tumbled mixed mineral specimens, likely quartz-rich rocks

Predominantly quartz (SiO₂), with possible jasper, agate, feldspar, and iron-oxide minerals

Black Tourmaline (Schorl)

Schorl (Sodium Iron Aluminum Borosilicate Hydroxide), NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH

Tumbled carnelian (red chalcedony)

Carnelian, a microcrystalline variety of quartz; SiO₂, commonly colored by iron oxides

Unidentified polished mineral fragment

Likely quartz-bearing stone; exact identification is impossible from the blurred photograph

Gemstone ring, likely emerald and opal

Green beryl (Be₃Al₂Si₆O₁₈), with probable common opal (hydrated amorphous silica, SiO₂·nH₂O)

Carved stone bowl or mortar

Uncertain; likely steatite (soapstone) or fine-grained volcanic stone

Mixed polished river pebbles, predominantly quartzite and quartz

Quartzite (SiO₂), quartz (SiO₂), with possible feldspar-rich and iron-stained lithologies

Rounded pink granite pebble

Granite, a coarse-grained felsic intrusive igneous rock composed primarily of quartz, feldspar, and minor mica or amphibole

Flint or chert, possibly a knapped stone tool

Microcrystalline quartz (SiO₂), commonly chalcedony with possible carbonaceous impurities

Banded Iron Formation (BIF)

Banded Iron Formation

Cut gemstone ring, likely diamond

Diamond (carbon, C), faceted gemstone; exact stone identification is uncertain from the image

Likely polished quartz-rich stone or calcite specimen

Uncertain; possibly quartz (SiO₂) or calcite (CaCO₃)

Granite

Phaneritic intrusive igneous rock (primarily SiO2)

Diamond

Diamond (pure Carbon, C)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Bismuth crystal

Bismuth (Bi), commonly laboratory-grown hopper crystal

Concretion or Geode (unbroken)

Varied (depending on mineral composition and cementing agent). For quartz-lined geodes, the scientific name of the dominant mineral would be Quartz (SiO2). For calcite-lined geodes, Calcite (CaCO3). Concretions are often composed of cryptocrystalline quartz (chert), calcite, or iron oxides.

Diamond (in jewelry setting)

Adamantine Carbon (C)

Possible weathered basalt or slag fragment

Basalt, chiefly plagioclase and pyroxene; identification is uncertain from the image

Blue Chalcedony and Picture Jasper Beads

Blue Chalcedony (SiO2), Picture Jasper (SiO2)

Diamond ring

Diamond (crystalline carbon, C)

Cultured pearls

Pearl; predominantly aragonite (CaCO₃) in nacre with organic conchiolin

Diamond (set in Gold)

Diamond (pure carbon, C)