Ferruginous Quartz
Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Hematite)
mineral
Category
Not A Geological Specimen
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Weathered quartz-rich rock, likely quartzite
Quartzite; predominantly quartz (SiO₂), possibly with feldspar and iron-oxide staining
metamorphic
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Druzy
Silicon Dioxide (SiO2)
mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Mineral
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Unidentified fine mineral/rock powder
Indeterminate from image; possibly crushed quartz-rich sand or finely milled rock
mineral
Conglomerate
Clastic Sedimentary Rock (Conglomerate)
sedimentary
Chert Nodule in Limestone
Microcrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
sedimentary
Pitted Sedimentary Rock / Cupstone
Sedimentary rock with weathering pit (arenite / sandstone)
sedimentary
Dark gray metamorphic rock, likely slate or phyllite
Slate/phyllite; chiefly fine-grained mica, chlorite, quartz, and clay-derived minerals
metamorphic
Quartz (Raw / Unpolished)
Silicon Dioxide (SiO2)
mineral
Quartz (Smoky/Milky variety)
Silicon Dioxide (SiO2)
mineral
Granite
Phaneritic Felsic Igneous Rock
igneous
Concretion with Geode Cavity
Ferruginous Sandstone Concretion with Quartz Center
sedimentary
Gneiss with Quartz Vein
Metamorphic Gneiss
metamorphic
Porphyritic Basalt or Spotted Pebble
Porphyritic volcanic rock with phenocrysts
igneous
Sandstone (Banded)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Petrified Wood (Silicified Fossil)
Silicified Wood (SiO2)
sedimentary
Schist
Mica Schist (Foliated Metamorphic Rock)
metamorphic
Tektite (Indochinite)
Tektite (High-silica impact glass)
igneous
Granitoid (with Epidote and Orthoclase)
Crystalline Felsic Intrusive Rock (containing SiO2, KAlSi3O8, and Ca2(Al2,Fe)(Si2O7)(SiO4)O(OH))
igneous
Lemon (Mock specimen mimicking Citrine/Sulfur)
Citrus x limon
Organic (Biological specimen)
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Schist (Greenschist / Mica Schist)
Schist (variable mineral composition, commonly containing quartz, feldspar, mica, chlorite)
metamorphic
Pyrite
Iron Sulfide (FeS2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Tiny amber-colored crystal or mineral fragment
Indeterminate from image; possibly quartz, citrine, topaz, or iron-stained feldspar
mineral
Quartz (Milky/Snow)
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Pebble with Basaltic and Quartz-rich Banding
Polymictic Lithic Pebble
sedimentary
White Quartz
Silicon Dioxide (SiO2)
mineral
Rounded quartz-rich sandstone or quartzite cobble
Quartz-dominated siliciclastic rock; likely sandstone, possibly weakly metamorphosed quartzite
sedimentary
Polished brecciated jasper or iron-rich chert
Silica-rich microcrystalline quartz (SiO₂), with iron-oxide/hydroxide staining; exact identification requires testing
sedimentary
Concretion, likely ironstone or sandstone concretion
Diagenetic mineral concretion, commonly quartz/calcite cement with iron oxides (goethite/hematite)
sedimentary
Banded Agate
Silicon Dioxide (SiO2)
mineral
Raw Quartz
Silicon Dioxide (SiO2)
mineral
Quartz (Milky or Iron-stained)
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral