Man Made Material

Jasper

Microcrystalline quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Synthetic Sapphire and Ion-X Glass

Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass

Diamond (Cut Gemstone)

Carbon (C)

Polished green aventurine (probable)

Quartz, SiO₂, with green fuchsite or chlorite inclusions

Iron-rich weathered stone, possibly hematite-rich ironstone

Hematite/goethite-bearing ironstone; predominantly Fe₂O₃ and FeO(OH)

Polished carnelian/chalcedony pebble

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony

Chert (Flint)

Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Mixed rock and mineral gravel

Predominantly granite/granodiorite, basaltic rocks, quartz, and possible gneiss; exact identification is uncertain from the image

Likely pale limestone or calcite-rich rock

Calcite-bearing limestone; chiefly calcium carbonate (CaCO₃)

Botryoidal chalcedony (possibly agate/geode material)

Microcrystalline quartz, SiO₂; commonly chalcedony with quartz-lined cavities and iron-oxide staining

Quartz-bearing iron-rich rock, possibly quartzite or hydrothermal breccia

Quartz (SiO₂) with iron oxides/hydroxides, likely limonite/goethite; exact host rock is uncertain from the photograph

Milky quartz-bearing rock, possibly quartzite

Quartz (SiO₂), likely in a quartzite or quartz-rich metamorphic matrix

Fossilized oyster shell in limestone

Bivalvia fossil; chiefly calcite (CaCO₃)

Mottled gabbro or diorite pebble

Coarse-grained mafic/intermediate intrusive rock; chiefly plagioclase feldspar plus pyroxene, with possible amphibole or biotite

Thulite in Matrix

Pink Zoisite - Ca2Al3(SiO4)3(OH)

Fossilized coral or carbonate fossil fragment

Calcareous fossil, likely colonial coral (order Hexacorallia; uncertain from image)

Likely granite or granitic gneiss

Quartz–feldspar–mica aggregate; possibly foliated granitic gneiss

Weathered quartz-rich rock, likely quartzite or altered sandstone

Quartzite (mostly microcrystalline quartz, SiO₂); exact identification is uncertain from the photograph

Weathered sandstone or iron-rich sedimentary fragment

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂-dominant)

Likely iron-rich chert or jasper

Microcrystalline quartz (SiO₂), variably stained by iron oxides/hydroxides

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible feldspar, mica, and iron-oxide staining

Chert (often called Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Peridot (Olivine)

Olivine ((Mg, Fe)2SiO4)

Conglomerate

Conglomerate (a clastic sedimentary rock)

Weathered limestone fragment

Calcitic limestone (mostly CaCO₃; possibly micritic limestone)

Weathered sandstone or iron-stained sedimentary rock

Quartz-rich sandstone, possibly ferruginous sandstone

Weathered sandstone or iron-rich mudstone fragment

Clastic sedimentary rock, likely quartz–feldspar sandstone with iron-oxide cement

Chert

Microcrystalline Quartz (SiO2)

Petrified Coral Fossil

Rugose or Tabulate Coral (Hexagonaria or similar fossilized cnidarian)

Sandstone

Sedimentary Rock (Quartz arenite)

Diamond

Diamond (pure Carbon, C)

Diamond

C (Native Carbon)

Diamond

Diamond (C)

Milky Quartz

Silicon Dioxide (SiO2)

Chert (variations include Flint)

Chert (SiO2)

Olivine (in Peridotite/Dunite form)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Sandstone

Sedimentary Rock (Quartz Sandstone)

Diamond

C (Carbon)

Green Fluorite

Calcium Fluoride (CaF2)

Kaolinite (Chalky Clay)

Kaolinite (Al2Si2O5(OH)4)