Sandstone with Hematite staining
Arenite with Fe2O3 inclusions
sedimentary
Category
Not A Rock (Synthetic Material)
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Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Sandstone (Ferruginous)
Arenite (composed primarily of SiO2 with Fe2O3 cement)
sedimentary
Serpentinite
Serpentinite (composed primarily of minerals in the serpentine group: (Mg,Fe)3Si2O5(OH)4)
metamorphic
Emerald in Matrix
Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities
mineral
Chert (or Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint Nodule)
Microcrystalline and Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (specifically Gray/Tan Bedded Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline quartz (SiO2)
sedimentary
Gabbro
Gabbro
igneous
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Banded sandstone pebble
Lithic or quartz-rich sandstone; exact composition requires testing
sedimentary
Peridot (Olivine)
Olivine ((Mg, Fe)2SiO4)
mineral
Rounded basalt pebble
Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with minor olivine or magnetite
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartz (Milky/Yellowish variety)
Silicon Dioxide (SiO2)
mineral
Scoria
Vesicular Basalt / Scoriaceous Basalt
igneous
Tumbled dark stone, likely basalt
Basalt (fine-grained mafic volcanic rock; commonly plagioclase, pyroxene, and minor olivine)
igneous
Shale
Shale (Lutite)
sedimentary
Ironstone Concretion
Siderite / Hematite-bearing Sedimentary Rock
sedimentary
Milky Quartz/Clear Quartz Cluster
Silicon Dioxide (SiO2)
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Cinnabar in Quartz
Silicon Dioxide (Quartz, SiO2) with Mercury Sulfide inclusions (Cinnabar, HgS)
mineral
Sandstone (likely Quartzose Sandstone)
Arenite (SiO2 principal composition)
sedimentary
Chert (Nodular)
Microcrystalline Silica (SiO2)
sedimentary
Basalt
Basalt (Mafic Igneous Rock)
igneous
Native American Hammerstone / Pitted Stone
Modified lithic artifact (often quartzite, basalt, or granite)
artifact / sedimentary or igneous rock
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone (Ferruginous)
Arenite (Fe2O3 staining)
sedimentary
Red Sandstone
Arenite (predominantly SiO2 with Fe2O3 staining)
sedimentary
Slate
Slate (foliated metamorphic rock)
metamorphic
Likely weathered iron-rich stone
Uncertain; possibly limonite/goethite-bearing rock
mineral
Coquina
Bioclastic Limestone (composed primarily of CaCO3)
sedimentary
Gravel and Pavement Aggregates
Unconsolidated rock fragments / detrital sediments
sedimentary
Chert (Flint Nodules)
Microcrystalline silica (SiO2)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Limestone with Calcite
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Greenstone
Metamorphic mafic rock (greenschist facies)
metamorphic
Greenstone / Serpentinite
Serpentine-group / Altered Mafic Rock
metamorphic
Granite
Granite (Felsic Intrusive Igneous Rock)
igneous
Diorite
Diorite (Intermediate intrusive igneous rock)
igneous