Polished black stone, likely black obsidian
Obsidian (volcanic glass; mainly SiO₂)
igneous
Category
Industrial Byproduct (Anthropogenic Rock)
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Quartz Vein in Sandstone
Sandstone with Hydrothermal Quartz (SiO2)
sedimentary
Porphyritic Basalt (River Rock)
Porphyritic Basalt
igneous
Rough Diamond
Diamond (pure Carbon, C)
mineral
Granite
Phaneritic Igneous Rock (Granite)
igneous
Rounded beach pebble
Lithology indeterminate; likely fine-grained sandstone, mudstone, or weathered volcanic rock
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Green Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Basalt (Vesicular or Porphyritic River Pebble)
Mafic Volcanic Rock (Aphanitic to Porphyritic Basalt)
igneous
Greenschist (or Serpentinite) with Quartz-Feldspar Vein
Metabasalt / Greenschist Facies Rock
metamorphic
Quartz pebble
Silicon Dioxide (SiO2)
mineral
Garnet Gneiss
Garnetiferous Gneiss
metamorphic
Tumbled rose quartz
Quartz, SiO₂; pink variety commonly called rose quartz
mineral
Fossilized shell fragment
Indeterminate fossil mollusk; likely a silicified or mineral-replaced bivalve/gastropod fragment
fossil
Quartz-lined vesicle in basalt (amygdaloidal basalt)
Amygdaloidal basalt with drusy quartz; predominantly plagioclase, pyroxene, and iron oxides
igneous
Likely rose quartz-bearing pegmatite
Quartz (SiO₂), probably with feldspar and iron-oxide staining
mineral
Amethyst Cluster
Quartz (SiO2 with iron impurities)
gemstone
Quartz (Tumbled)
Silicon Dioxide (SiO2)
mineral
Diamond
Carbon (C)
gemstone
Pegmatite
Igneous Pegmatite (Quartz-Feldspar-Mica)
igneous
Fossil brachiopod shell
Likely spiriferid or strophomenid brachiopod; calcium carbonate (primarily calcite)
fossil
Pegmatite
Igneous Pegmatite
igneous
Limestone River Pebble
Calcium carbonate (CaCO3) - micritic limestone
sedimentary
Green Calcite
Calcium Carbonate (CaCO3)
mineral
Yellow Calcite
Calcium Carbonate (CaCO3)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Bumblebee Jasper
Calcite with Arsenic and Sulfur inclusions
sedimentary
Sapphire (Blue/Violet Rough)
Corundum (Al2O3)
gemstone
Agate
Silicon dioxide (Chalcedony), SiO2
sedimentary
K-Feldspar (Potassium Feldspar)
Potassium Feldspar (Microcline or Orthoclase), KAlSi3O8
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz (Field Stone)
Silicon Dioxide (SiO2)
mineral
Amethyst (Rough Crystal)
Silicon Dioxide (SiO2) with iron impurities
mineral
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
sedimentary
Orange Calcite
Calcium Carbonate (CaCO3)
mineral
Chert (Jasper/Limonitic Chert)
Cryptocrystalline Quartz (SiO2) with Iron Oxide (FeO(OH)) inclusions
sedimentary
Magnetite (Lodestone variant potential)
Magnetite (Fe3O4)
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Diamond (Cut Gemstones in Jewelry)
Carbon (C)
gemstone
Cubic Zirconia (Diamond Simulant)
Zirconium Dioxide (ZrO2)
gemstone
Banded Calcite (Honey Calcite)
Calcium Carbonate (CaCO3)
mineral
Olivine (Peridot Stone)
(Mg, Fe)2SiO4 (Magnesium Iron Silicate)
mineral