Man Made

Engineered Quartz (Quartzite look-alike)

Silicon Dioxide (SiO2) composite

Bog Iron / Limonite Concretion

Goethite/Limonite mixture (FeO(OH)·nH2O)

Basalt

Basalt

Coquina

Biogenic Limestone (Coquina)

Diamond (or Cubic Zirconia)

Carbon (C) or Zirconium Dioxide (ZrO2)

Vesicular Basalt (or Scoria)

Vesicular Basalt

Turquoise

Turquoise, CuAl6(PO4)4(OH)8·4H2O

Diamond

Cubic carbon (C)

Chert

Chert (Microcrystalline Quartz)

Sandstone (Quartzose)

Arenite (composed primarily of SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Granite

Phaneritic Felsic Igneous Rock

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite

Granite

Granite (Phaneritic Quartz-Feldspar intrusive rock)

Rutilated Quartz

Silicon Dioxide (SiO2) with Titanium Dioxide (TiO2) inclusions

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Diamond

Diamond (pure carbon C)

Diamond

Carbon (C)

Pearl

Calcium Carbonate (CaCO3) - Aragonite/Calcite

Chert or Jasper

Microcrystalline Quartz (SiO2)

Granodiorite / Granite (Weathered)

Granodiorite

Chert / Flint

Silicon Dioxide (SiO2)

Brecciated Jasper

Brecciated Jasper (Microcrystalline Quartz / SiO2)

Green Aventurine

Silicon Dioxide (SiO2+KAl2(AlSi3O10)(OH)2)

Gabbro

Gabbro (Mg, Fe)2Si2O6 / (Ca, Na)(Al, Si)4O8

Granite

Granite (composed primarily of Quartz, Feldspar, and Mica)

Chert (with Quartz)

Microcrystalline Quartz (SiO2)

Chert (Chalcedony/Agate variety)

Silicon Dioxide (SiO2)

Diamond (in Jewelry)

Carbon (C)

Belemnoit (Fossil)

Belemnoidea (Order), Rostrum / Guard

Turquoise

Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O

Chalk

Carbonate rock (mainly CaCO3)

Chert

Silicon dioxide (SiO2)

Quartzite

Metamorphic Rock (Mainly SiO2)

Chert (Cherty Shale / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Granite

Granite (a plutonic rock)

Granite

Intrusive Igneous Rock (Granitic)

Sandstone

Arenite (with iron oxide cement)

Sandstone

Arenite

Sandstone

Arenite

Sandstone

Arenite (mostly SiO2)