Chert (Jasper variety)
Silicon Dioxide (SiO2)
Category
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Quartz heart (likely milky/included quartz)
Quartz, silicon dioxide (SiO₂)
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
Blue Apatite
Fluorapatite / Chlorapatite [Ca5(PO4)3(F,Cl,OH)]
Chert or Jasper
Microcrystalline Quartz (SiO2)
Chert (varietal Flint)
Microcrystalline quartz (SiO2)
Pearl
Calcium Carbonate (CaCO3) with Conchiolin
Tumbled chalcedony (likely carnelian/agate)
Microcrystalline quartz, SiO₂; chalcedony, with possible iron-oxide coloring
Chert or heavily weathered flint
Microcrystalline quartz (SiO₂), likely chert/flint
Milky Quartz
Silicon Dioxide (SiO2)
Crescent Pebble
Weathered Quartzite or Sandstone Fragment
Kidney Stone (Calcium Oxalate / Uric Acid)
Calcium Oxalate Monohydrate (Whewellite) / Calcium Oxalate Dihydrate (Weddellite)
Riverstone (Sandstone Pebble)
Arenite (SiO2 with various lithic fragments)
Goldstone
Aventurine Glass (Man-made glass with copper inclusions)
Petrified Wood
Silicified Wood (primarily SiO2)
Metal Alloy (Likely Pewter or Sterling Silver)
Not a natural geological specimen; composed of refined metals. If pewter, it's a tin-based alloy. If sterling silver, it's 92.5% silver and 7.5% other metals (usually copper).
Chert (containing Flint and Chalcedony)
Microcrystalline Quartz (SiO2)
Chert Arrowhead (Projectile Point)
Microcrystalline Quartz (Chert or Flint)
Weathered pegmatite or feldspar-rich granite fragment
Granitic pegmatite, composed mainly of potassium feldspar and quartz, with minor mica; exact identification is uncertain from the photograph
Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
Biological Bone (Patella/Knee)
Patella (part of the Human Skeletal System)
Tumbled chalcedony (likely pale agate or quartz pebble)
Microcrystalline silica, SiO₂ (chalcedony; possibly quartz-rich agate)
Common Opal
SiO2·nH2O (Hydrated Silicon Dioxide)
Chert (variations include Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Obsidian (Blue)
Volcanic Glass (SiO2)
Smoky Quartz
Silicon Dioxide (SiO2)
Pyrite in Quartz (Drill Core)
Silicon Dioxide (SiO2) with Iron Sulfide (FeS2) inclusions
Chert (Arrowhead Preform or Point)
Chert (Microcrystalline Quartz, SiO2)
Likely tumbled jasper or iron-rich chert
Microcrystalline quartz (SiO₂), potentially hematite/goethite-bearing
Brick
Fired clay or Ceramic material (no specific mineralogical scientific name as it's a composite)
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Likely iron-rich slag or weathered ironstone
Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag
Agate
Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony
Green Glass Cullet / Recycled Glass
Amorphous Silicon Dioxide (SiO2) with various metal oxides
Tumbled milky quartz pebble
Quartz (silicon dioxide, SiO₂), opaque-to-translucent milky variety
Chert
Microcrystalline quartz (SiO2)
Chert (and Limestone)
Silicon Dioxide (SiO2)
Tumbled jasper, likely picture or brecciated jasper
Microcrystalline quartz (SiO₂) with iron-oxide and other mineral impurities
Dyed Quartz (imitating Emerald/Green Quartz)
Silicon Dioxide (SiO2) with artificial pigment
Pearl
Calcium Carbonate (Aragonite or Calcite) and Conchiolin
Flint or chert flake
Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities
Tumbled green aventurine (probable)
Quartz, SiO₂, with green fuchsite mica inclusions