Mineral, Specifically A Rock Fragment

Quartz Crystal Fragment

Silicon Dioxide (SiO2)

Chert (specifically Pink/Tan Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone (with garnet granules)

Clastic sedimentary rock (primarily SiO2 with Fe3Al2(SiO4)3 inclusions)

Sandstone (Red Flagstone)

Clastic sedimentary rock (primarily Quartz - SiO2)

Biotite (Black Mica)

Biotite - K(Mg,Fe)3(AlSi3O10)(F,OH)2

Sandstone (specifically Arkose or Quartz Arenite)

Arenite (primarily SiO2 with possible Feldspar)

Chert (Arrowhead Fragment)

Chert / Microcrystalline Silicon Dioxide (SiO2)

Limestone (specifically Chalky Limestone)

Calcium Carbonate (CaCO3 / Calcite)

Pebble

Lithic fragment / Rounded rock fragment

Small white mineral fragment

Indeterminate; possibly quartz, calcite, or feldspar

Limestone (specifically a Crushed Aggregate fragment)

Calcium Carbonate (CaCO3)

Weathered mineralized rock fragment

Indeterminate; likely quartz–feldspar-rich lithic material with iron-oxide staining

Chert (Nodule fragment)

Silicon Dioxide (SiO2)

Mammoth Tooth Fragment

Mammuthus primigenius (fossilized dentin and enamel)

Unidentified brown mineral/rock fragment

Indeterminate from image; possibly iron-stained quartz, feldspar, or weathered limonite

Fuchsite

Chromium-rich Muscovite Mica

Milky Quartz

Silicon Dioxide (SiO2)

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock

Pink Granite

Granite (composed primarily of Quartz, K-Feldspar, and Plagioclase)

Smooth river pebble

Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert

Chert (Flint Arrowhead)

Microcrystalline Quartz (SiO2)

Banded Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica)

Limestone (specifically Fossiliferous Limestone)

Calcium Carbonate (CaCO3)

Drupa or Druzy Quartz on Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Jasper Breccia

Silicon Dioxide (SiO2) with iron inclusions

Weathered granitic rock fragment

Granite, predominantly quartz–feldspar–mica assemblage

Unidentified dark mineral/rock fragment

Indeterminate; appearance may fit a sulfide-bearing rock or iron-rich mineral

Quartz-rich mineral fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Quartz Geode / Druzy Quartz

Silicon Dioxide (SiO2)

Granite fragment

Granite; chiefly quartz, alkali feldspar, and plagioclase, with minor mica or amphibole

Conglomerate

Conglomerate (clastic sedimentary rock)

Granite fragment

Granite (Felsic Plutonic Rock)

Weathered quartz-bearing rock fragment

Indeterminate; likely quartz-rich granite or silicified host rock with iron-oxide staining

River Pebble

Quartzo-feldspathic rock fragment

Unidentified gray stone

Likely quartz-rich stone; exact identification is not possible from the image

Banded Iron Formation (Fragment)

Banded Iron Formation (BIF)

Quartz pebble in concrete

Quartz (SiO₂), embedded in Portland-cement concrete

Red Sandstone

Arenite (primarily Quartz with Hematite cement)

Fossiliferous Limestone with Brachiopod Mold

Calcium Carbonate (CaCO3) matrix containing Brachiopoda fossil impressions

Small dark mineral/rock fragment

Indeterminate; possibly magnetite-bearing basalt or iron-rich slag

Quartz-bearing rock fragment

Likely quartz (SiO₂) with iron-oxide staining and possible host-rock grains

Concrete Fragment

Hardened Portland cement and mineral aggregate