Obsidian
Obsidian (Extrusive Volcanic Glass)
igneous
Category
Man Made Material (Anthropogenic 'Mineraloid')
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Serpentinized ultramafic rock with magnesite
Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with likely magnesite (MgCO₃) and minor chromite/magnetite
metamorphic
Basalt
Basalt
igneous
Sodalite beads
Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, likely with minor lazurite/pyrite or calcite inclusions
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Granite
Granite (plutonic igneous rock)
igneous
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Red jasper (likely brecciated jasper)
Jasper, microcrystalline quartz (SiO₂), colored mainly by iron oxides
mineral
Polished serpentinite pebble
Serpentinite; primarily serpentine-group minerals (Mg3Si2O5(OH)4), with possible magnetite and talc
metamorphic
Mahogany Obsidian Arrowhead
Volcanic Glass with Hematite/Magnetite inclusions (Amorphous Silicon Dioxide)
igneous
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Tumbled jasper or brecciated jasper
Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide and dark mineral inclusions
mineral
Milky Quartz with Hematite/Limonite staining
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenite (composed primarily of Quartz: SiO2)
sedimentary
Quartz crystal fragment
Quartz (silicon dioxide, SiO₂)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Fossilized echinoid (sea urchin), likely a flint/chalk-associated test
Echinoid fossil; likely a regular echinoid such as Echinocidaris or related taxon, composed mainly of recrystallized calcite (CaCO₃)
fossil
Diabase (Dolerite)
Diabase / Dolerite
igneous
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Milky quartz–rich rock
Quartz (SiO₂), likely massive milky quartz with minor dark inclusions
mineral
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Granodiorite (River Pebble)
Granodiorite
igneous
Land Snail Shell
Gastropoda (Calcium Carbonate, CaCO3)
fossil
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Granite Pebble
Granite (composed primarily of Quartz, Feldspar, and Mica)
igneous
Black obsidian (probable)
Volcanic glass; primarily SiO₂-rich rhyolitic composition
igneous
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Quartzite
Metamorphic Quartz Sandstone
metamorphic
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Chert (Nodule)
Cryptocrystalline Quartz (SiO2)
sedimentary
Tumbled brown jasper
Microcrystalline quartz/chalcedony (SiO₂), commonly iron-oxide stained
sedimentary
Likely milky quartz fragment
Quartz (silicon dioxide, SiO₂), possibly with iron-oxide or mica inclusions
mineral
Limestone (River Pebble)
Calcite (Calcium Carbonate) - CaCO3
sedimentary
Milky quartz with iron-oxide staining
Quartz (SiO₂), likely ferruginous milky quartz
mineral
Tumbled agate (probable moss or dendritic agate)
Microcrystalline quartz, SiO₂, with iron/manganese dendritic inclusions
mineral
Black Jasper (Etched)
Silicon Dioxide (SiO2) with impurities
mineral
Likely petrified wood or silicified fossil fragment
Silicified wood; predominantly microcrystalline quartz (SiO₂)
fossil