Fossilized oyster shell / oyster reef limestone
Predominantly calcite (CaCO₃), commonly fossil bivalve shells such as Ostrea or Crassostrea; matrix is bioclastic limestone
fossil
Category
Non Geological
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Quartzite
Quartzite (Metamorphosed quartz sandstone)
metamorphic
Obsidian
Volcanic Glass (SiO2)
igneous
Fossilized bone, likely a large vertebrate limb or rib fragment
Petrified bone; exact taxon indeterminate from the image
fossil
Obsidian
Volcanic Glass (mostly SiO2)
igneous
Iron-rich weathered rock or limonite/goethite nodule
Limonite (mixture dominated by goethite, FeO(OH)·nH₂O), possibly with quartz or clay
mineral
Snowflake Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Opalite
Synthetic Opalised Glass
Mineral (Synthetic / Man-made)
Obsidian
Volcanic Glass (SiO2)
igneous
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Small brown pebble or possible shell fragment
Unidentified natural clast; the image is too small and blurred for reliable identification
sedimentary
Tektite
Natural Impact Glass
meteorite
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Obsidian
Obsidian (principally SiO2)
igneous
Obsidian
Volcanic Glass (SiO2 rich)
Igneous
Quartzite
Metamorphic Quartz-rich Rock
metamorphic
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian
Volcanic glass (SiO2-rich extrusive igneous rock)
igneous
Tumbled pink quartz, likely rose quartz
Rose quartz; predominantly silicon dioxide (SiO₂), commonly colored by trace iron, titanium, or manganese
mineral
Fossil bone or tooth fragment
Indeterminate fossilized vertebrate bone/tooth; taxonomic identification is not possible from this blurred image
fossil
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
igneous
Quartzite
Metamorphic Quartz Rock (SiO2)
metamorphic
Quartzite
Metamorphic Quartz Arenite
metamorphic
Polished turquoise cabochon pendant
Turquoise, hydrated copper-aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O; likely stabilized or matrix-bearing material
mineral
Dyed or treated turquoise-like tumbled stone
Likely turquoise (CuAl₆(PO₄)₄(OH)₈·4H₂O), though blue-green magnesite or howlite imitation is possible
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Weathered mafic rock, likely basalt or gabbro
Basalt–gabbroic rock; chiefly plagioclase feldspar and pyroxene, with possible olivine and magnetite
igneous
Tumbled turquoise (likely matrix-bearing)
Turquoise, hydrated copper aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O
mineral
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide) with impurities
igneous
Pale green calcite crystal
Calcite (CaCO₃), likely a translucent cleavage fragment
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian Arrowhead
Volcanic Glass (70% or more SiO2)
Igneous
Weathered metallic meteorite candidate
Unclassified meteorite; appearance possibly iron meteorite or stony-iron material
meteorite
Obsidian
Volcanic glass (high silica SiO2)
igneous
Snowflake Obsidian
Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)
Igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Weathered sandstone
Quartz-rich sandstone (clastic sedimentary rock)
sedimentary
Rounded pebble, likely limestone
Microcrystalline calcite (CaCO₃), probably micritic limestone
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Obsidian
Obsidian (Volcanic Glass)
igneous