River Rock (Basalt or Sandstone)
Clastic Sedimentary Rock or Extrusive Mafic Igneous Rock
igneous or sedimentary
Category
Igneous Or Sedimentary
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Basalt and Quartz Pebble
Basalt (Igneous) and Quartzite/Quartz (SiO2) pebble
igneous and sedimentary
River Stones (Basalt and Sedimentary Rock)
Basalt (dark specimen) and Siltstone/Mudstone (reddish specimen)
igneous and sedimentary
Basalt or Siltstone Pebbles
Mafic volcanic rock (Basalt) or Indurated Siltstone
igneous or sedimentary
River Pebbles (Basalt and Graywacke/Limestone)
Mafic Volcanic Rock / Impure Sandstone
igneous and sedimentary
River Stone (Basalt or Siltstone)
Mafic Volcanic Rock or Clastic Sedimentary Rock
igneous or sedimentary
Pebble (Likely Basalt or Siltstone)
Clastic sedimentary rock or mafic volcanic rock
Igneous or Sedimentary
Banded River Cobble with Mafic Dike
Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion
igneous and sedimentary
Likely polished black stone; possibly basalt or black chert
Indeterminate from the blurred image; candidates include basalt (mafic volcanic rock) or microcrystalline quartz (chert)
igneous or sedimentary
Wishing Stone (Basalt or Mudstone with Quartz/Calcite Veins)
Hydrothermally veined Basalt (SiO2/CaCO3 intrusions)
igneous or sedimentary
Granite (phaneritic background) with Limestone/Calcite carving
Felsic Igneous Plutonic Rock (background) / Calcium Carbonate (CaCO3) (carving)
igneous and sedimentary
Jasper and Basalt Pebble
Polymineralic lithic pebble
igneous and sedimentary
Wishing Stone (Basalt or Siltstone with Quartz/Calcite Vein)
Basalt (SiO2+MgO+FeO) or Siltstone with a Quartz (SiO2) or Calcite (CaCO3) vein
igneous or sedimentary
Wishing Stone (Basalt or Chert with Quartz Veins)
Basalt or microcrystalline Quartz (Chert) with localized hydrothermal Quartz (SiO2) veining
igneous or sedimentary
Rounded river pebbles, likely basalt and sandstone/conglomerate
Probable basalt (dark specimen) and ferruginous sandstone or weathered conglomerate (tan specimen)
igneous and sedimentary
River Rock (Basalt/Greywacke pebbles)
Fluvial gravel primarily composed of Mafic Volcanic Rock (Basalt) or Lithic Sandstone (Greywacke)
igneous and sedimentary
River Pebbles (Tumbled Quartz and Basalt)
Silicon Dioxide (SiO2) for white quartz; Mafic Volcanic Rock for basalt
igneous and sedimentary
Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Mineral (or mineraloid if microcrystalline)
Ruby in Zoisite
Ruby (α-Al2O3) embedded in Zoisite (Ca2Al3(SiO4)3(OH)) with some Hornblende
Metamorphic Rock (composed of multiple minerals)
Banded Gneiss
Gneiss (variable mineral composition)
metamorphic
Epidote in Quartz
Quartz with Epidote inclusions (SiO2 with Ca2(Al,Fe)3(SiO4)3(OH) inclusions)
Mineral
Apatite
Apatite group mineral (e.g., Fluorapatite - Ca5(PO4)3F, Chlorapatite - Ca5(PO4)3Cl, Hydroxylapatite - Ca5(PO4)3(OH))
mineral
Garnet (Red Garnet)
Garnet Group. The red varieties seen in jewelry are typically Almandine (Fe3Al2(SiO4)3), Pyrope (Mg3Al2(SiO4)3), or a mix of the two (pyrope-almandine series).
Mineral (specifically, a variety of the mineral species Pyrope-Almandine Garnet)
Banded Gneiss
Gneiss (pronounced "nice")
metamorphic
Gneiss
Gneiss (a type of metamorphic rock)
Metamorphic Rock
Banded River Rock / Gneiss (highly weathered)
Gneiss
Metamorphic rock
Gneiss
Feldspathic biotite gneiss; a high-grade metamorphic rock composed mainly of quartz, feldspar, and mica
metamorphic
Carnelian
Chalcedony (cryptocrystalline quartz), SiO2
Mineral
Quartz / Limestone Gravel
SiO2 (Silicon Dioxide) and CaCO3 (Calcium Carbonate)
igneous and sedimentary mixture
Mixed collection of natural stones
Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks
igneous, metamorphic, sedimentary
Epidote (or Epidote-rich rock)
Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).
Mineral, often found in metamorphic rocks but also in sedimentary and igneous rocks
Red Chalcedony (likely dyed)
Chalcedony (a variety of Quartz), SiO2
Mineral (Cryptocrystalline Quartz)
Obsidian and Green Calcite
Volcanic Glass and Calcium Carbonate (CaCO3)
igneous and sedimentary/mineral
Mixed Crushed Stone
Aggregate (varied mineral composition)
igneous and sedimentary mixture
River Cobbles (Basalt, Quartzite, and Sandstone mix)
Fluvial detritus (primarily SiO2, Plagioclase, and Pyroxene mix)
Mixed: Igneous and Sedimentary
River Rock (likely Basalt or Greywacke)
Basalt or Lithic Sandstone
Igneous or Sedimentary (water-worn)
Painted Garden Rock (likely Granite or Limestone base)
Silicon Dioxide (SiO2) / Calcium Carbonate (CaCO3) based substrate with Acrylic/Enamel pigments
igneous or sedimentary (anthropogenic modification)
Quartz with Basalt inclusion
Silicon Dioxide (SiO2) with mafic silicate rock
igneous and sedimentary/metamorphic mix
Green Slag Glass (Cullet)
Amorphous Silica (Industrial Glass Byproduct)
Synthetic/Byproduct (Non-igneous, non-sedimentary, non-metamorphic)
Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Common Opal
Hydrated amorphous silica (SiO2·nH2O)
mineral
Kaolinite (Kaolin)
Kaolinite (Al2Si2O5(OH)4)
mineral