Chert
Chert (Microcrystalline Quartz)
sedimentary
Category
Anthropogenic (Man Made Industrial Deposit)
Browse anthropogenic (man made industrial deposit) specimens identified by the Rock Identifier community.
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Sea Glass (Kelly Green)
Amorphous Silica (Silicon Dioxide with Iron/Chromium additives)
Anthropogenic specimen (Man-made material)
Jasper / Chert (Red)
Cryptocrystalline quartz (SiO2)
Sedimentary / Mineral
Chalk
Micrite (primarily Calcium Carbonate, CaCO3)
sedimentary
Limestone
Sedimentary Rock (Primarily CaCO3)
sedimentary
Diamond in Kimberlite
Diamond in Kimberlite Matrix (Diamond: C, Kimberlite: complex Potassic Peridotite)
igneous
Tumbled epidote-bearing rock (likely epidote–quartz–feldspar aggregate)
Epidote-rich metamorphic rock; minerals likely epidote (Ca₂(Al,Fe)₃Si₃O₁₂(OH), quartz, feldspar, and dark amphibole/biotite)
metamorphic
Chalcedony (likely agate)
Microcrystalline quartz, SiO₂; agate is banded chalcedony
mineral
Red agate bead (likely dyed or treated)
Agate, a microcrystalline variety of quartz; SiO₂
gemstone
Diamond
Carbon (C)
gemstone
Diamond
Carbon (C)
mineral
Possible calcite crystal fragment
Calcite (CaCO₃), tentative identification
mineral
Terrazzo (with Marble and Granite fragments)
Cementitious or resinous composite containing Calcium Carbonate (CaCO3) and Silicates
sedimentary (man-made composite)
Weathered fossil shell fragment
Likely a fossilized bivalve or gastropod fragment; exact taxon cannot be determined from one view
fossil
Possible basalt or iron-rich slag
Basalt (tentative; identification uncertain from image)
igneous
Possible ironstone concretion or weathered mineral nodule
Iron-oxide-rich concretion, likely goethite/limonite; identification uncertain from the photo
sedimentary
Limestone
CaCO3 (principally Calcite)
sedimentary
Small dark rock fragment
Uncertain; possibly weathered basalt or slag
mineral
Iron Slag
Iron smelting byproduct (Glassy/vesicular silicate)
anthropogenic / industrial byproduct
Dark gray rounded stone, possibly basalt or slag
Uncertain; likely fine-grained basalt (plagioclase–pyroxene) or iron-rich industrial slag
igneous
Diamond (as featured in jewelry)
Diamond (C - pure carbon)
mineral
Chert (Chalcedony/Agate variety)
Silicon Dioxide (SiO2)
sedimentary
Sandstone
Arenite (SiO2 based clastic rock)
sedimentary
Multicolor quartz bead bracelet
Quartz (silicon dioxide, SiO₂); bead colors may be from different varieties or treated quartz
gemstone
Siltstone Pebble
Siltstone (composed of microscopic quartz and clay minerals)
sedimentary
Quartz-veined Metamorphic Rock
Quartz Vein in Phyllite or Schist (SiO2 in Silicate Matrix)
metamorphic
Tumbled brown tourmaline (likely dravite)
Tourmaline-group mineral; probably dravite, NaMg₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
mineral
Chert / Jasper
Silicon Dioxide (SiO₂)
sedimentary
Chert
Silicon dioxide (SiO2)
Sedimentary
Fossil crinoid columnal in limestone
Crinoidea indet.; calcitic ossicle (CaCO₃)
fossil
Possible obsidian (black volcanic glass)
Obsidian; natural silica-rich volcanic glass, composition typically rhyolitic
igneous
Crinoid stem fossil
Crinoidea
fossil
Diamond
Cubic carbon (C)
mineral
Fossilized sea urchin
Echinoid test, likely a regular sea urchin; calcite (CaCO₃)
fossil
Likely black beach pebble
Undetermined; possibly basalt, chert, or dark slate
sedimentary
Sandstone (Ferruginous)
Arenite (SiO2 with Fe2O3 inclusions)
sedimentary
Diamond
Carbon (C)
gemstone
Tumbled chalcedony (likely moss or dendritic agate)
Microcrystalline quartz, SiO₂, with iron-oxide inclusions
mineral
Red-and-brown agate bead bracelet
Agate, a microcrystalline variety of quartz (SiO₂), likely colored chalcedony/carnelian
mineral
Polished white chalcedony or milky quartz pebble
Chalcedony, microcrystalline quartz (SiO₂), possibly with iron-oxide staining or a minor mineral inclusion
mineral
Chert (Chert / Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Flint (gray chert)
Microcrystalline quartz (SiO₂), a variety of chert
sedimentary