Quartz-rich granite or pegmatitic rock
Granite/pegmatite; chiefly quartz (SiO₂), feldspar, and minor mica
igneous
Category
Synthetic Material (Not A Rock Or Mineral)
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Fossilized cylindrical shell or bone fragment
Indeterminate biogenic carbonate or phosphatic fossil; possible fragment of a tubular shell (e.g., scaphopod) or hollow bone
fossil
Iron-stained quartz-rich rock, possibly goethite-bearing quartz
Quartz (SiO₂) with iron oxides/hydroxides, likely goethite or limonite
mineral
Likely polished dark stone or glassy mineral bead
Indeterminate; possibly obsidian, hematite, or a dark agate
mineral
Petrified Wood
Silicified Wood (Silicon Dioxide - SiO2)
fossil
Petrified Wood
Silicified wood (Quartz replacement of organic wood structure)
fossil
Serpentinite
Serpentinite (composed primarily of minerals in the Serpentine group)
metamorphic
Sandstone (Quartzose Sandstone)
Arenite (primarily SiO2 with minor Fe2O3)
sedimentary
Slate
Slate (Metamorphic rock)
metamorphic
Vesicular quartz-rich rock, possibly weathered rhyolite or hydrothermal quartz
Likely quartz (SiO₂) with altered feldspar, iron oxides, and cavities; exact identification requires testing
igneous
Polished granite
Granite; chiefly quartz, feldspar, and mica/amphibole
igneous
Jasper and Quartz Breccia
Silica breccia (SiO2)
sedimentary
Ferruginous Sandstone (Ironstone)
Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Fossil Coral
Rugosa or Tabulata coral fossil (Calcium Carbonate, CaCO3)
fossil
Siltstone Pebble
Siltstone (fine-grained siliciclastic sedimentary rock)
sedimentary
Shale
Fissile Mudrock (Clay-rich Sedimentary Rock)
sedimentary
Greenschist (or Serpentinite with Manganese Dendrites)
Greenschist facies metamorphic rock
metamorphic
Chert Nodule
Chert (Microcrystalline Silicon Dioxide, SiO2)
sedimentary
Chrysocolla (Copper Ore matrix)
Chrysocolla (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O)
mineral
Orange chromium diopside (likely tumbled)
Diopside, CaMgSi₂O₆; orange color may reflect iron-rich composition or surface treatment/inclusion
mineral
Tumbled Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Limestone (River Pebble)
Calcium Carbonate (CaCO3)
sedimentary
Banded Chert (likely Flint or Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Yellow Quartz (Citrine Quartz Pebble)
Silicon Dioxide (SiO2)
mineral
Weathered granite or granitic gneiss pebble
Granite; mainly quartz (SiO₂), feldspar, and mica, with possible gneissic alteration
igneous
Sandstone (Graywacke type)
Clastic Sedimentary Rock (Lithic Sandstone)
sedimentary
Sandstone (Ferruginous)
Arenite (with Iron Oxide cement)
sedimentary
Granite
Granite
igneous
Khondalite
Garnet-Sillimanite-Graphite Gneiss
metamorphic
Sandstone
Arenite (Siliclastic sedimentary rock, primarily SiO2)
sedimentary
Travertine (Calcareous Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Polished orbicular jasper / brecciated jasper
Jasper, microcrystalline quartz (SiO₂), with iron-oxide and clay-rich inclusions
sedimentary
Sandstone with Ironstone Concretion
Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Petrified Wood
Silicified Wood (mainly Quartz/Chalcedony, SiO2)
fossil
Black Obsidian
Volcanic Glass (SiO2 with impurities)
igneous
Mudstone
Argillite
sedimentary
Orbicular jasper (likely ocean jasper)
Silica-rich microcrystalline quartz/chalcedony with iron-oxide and other mineral inclusions; commonly classified as orbicular jasper
mineral
Gabbro (River Cobble)
Gabbro (mafic intrusive rock)
igneous
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of organic matter)
fossil
Orthoclase Feldspar
Orthoclase (KAlSi3O8)
mineral