Man Made Composite

Fossil crocodilian skull and jaws

Crocodyliform fossil; exact genus and species cannot be determined from the image

Basalt

Basalt (Mafic volcanic rock)

Quartzite

Quartzite (Metamorphosed Sandstone)

Quartzite

Metamorphic Quartzite (SiO2)

Basalt

Basalt (containing plagioclase, pyroxene, and olivine)

Diamond

Carbon (C)

Quartzite

Metamorphic Quartzite (SiO2)

Sandstone

Arenite (variable SiO2 composition)

Goldstone (aventurine glass)

Synthetic copper-bearing soda-lime glass; commonly sold as red goldstone

Diamond

Carbon (C)

Tumbled chalcedony or quartz pebble

Microcrystalline quartz, SiO₂ (likely chalcedony); exact identification is uncertain from the image

Botryoidal chalcedony with iron-oxide staining

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony

Likely tumbled epidote-bearing rock or green jasper

Epidote-group silicate, possibly in a jasper or serpentinite matrix

Smoky Quartz Cluster

Smoky Quartz (Silicon Dioxide - SiO2)

Granite

Granite (a plutonic igneous rock)

Chalk

Calcium Carbonate (CaCO3)

Orange-yellow mineral fragment (possibly sulfur)

Unidentified; color suggests native sulfur (S), but the image is insufficient for confident identification

Red Quartzite

Quartzite (Metamorphic quartz sandstone)

Aragonite

Aragonite (Calcium Carbonate - CaCO3)

Blue-green quartz-rich stone, possibly chrysoprase or aventurine

Uncertain; likely quartz (SiO₂) with green coloration from nickel-bearing minerals or inclusions

Diamond

Carbon (C)

Sandstone (Pebble)

Sandstone (SiO2 with matrix/cement)

Diamond

Carbon (C)

White quartz geode

Quartz geode; predominantly microcrystalline and drusy SiO₂

Weathered conglomeratic river cobble

Polymictic conglomerate or breccia, likely matrix-supported

Diamond (in a jewelry setting)

Cubic Carbon (C)

Likely weathered sandstone fragment

Sandstone, composed mainly of quartz (SiO₂) and feldspar grains in a clay, silica, or iron-oxide cement

Pearl

Aragonite (CaCO3 with conchiolin)

Pearl necklace

Pearl, primarily aragonite (CaCO₃) and conchiolin

Diamond (faceted)

Diamond (Pure Carbon, C)

Quartzite

Metamorphic quartz rock (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Diamond

Carbon (C)

Concrete or asphalt-like aggregate surface with a dark fragment

Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock

Pearl

Calcium Carbonate (CaCO3) with Conchiolin

Sandstone

Arenite (specifically sublithic or quartz arenite)

Sandstone (Ferruginous)

Arenite (Fe2O3 stained)

Quartzite

Metamorphic Quartzite (SiO2)

Pyrite

Iron Sulfide (FeS2)

Specular Hematite (Iron Ore)

Iron(III) oxide (Fe2O3)

Sandstone

Arenite (SiO2 primarily)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)