Metamorphic (Man Made)

Pale green aventurine (likely quartz) sphere

Quartz, SiO₂; possibly pale green aventurine, with color from inclusions or treatment

Dark quartz point (possibly smoky quartz)

Quartz, SiO₂; the dark color may indicate smoky quartz, but the image is insufficient to confirm

Red Sandstone

Arenite (Ferruginous Sandstone)

Muscovite mica

Muscovite, KAl₂(AlSi₃O₁₀)(OH)₂

Sandstone (Pebble)

Sandstone (arenite, arkose, wacke depending on composition)

Quartz-rich pebble

Mostly quartz (SiO₂), possibly a quartzite or vein-quartz fragment

Likely amphibolite (hornblende-rich metamorphic rock)

Amphibolite, composed chiefly of amphibole (commonly hornblende) and plagioclase feldspar

Rounded quartz-rich cobble, likely quartzite

Quartzite; predominantly SiO₂ (recrystallized quartz)

Likely slate fragment

Slate; predominantly fine-grained mica/clay minerals and quartz

Likely weathered gneiss or mica-rich schist

Foliated metamorphic rock, probably quartz–feldspar–biotite gneiss/schist

Milky Quartz

Silicon Dioxide (SiO2)

Weathered quartz-rich rock, possibly quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂)

Pebble (likely Quartz or Chert)

SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.

Biotite (Black Mica)

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

Quartz (likely Milky Quartz)

Quartz (SiO₂ - Silicon Dioxide)

Obsidian (Black)

Obsidian (High-silica volcanic glass)

Diabase (Greenstone)

Diabase (Dolerite)

Likely quartz fragment

Quartz (silicon dioxide, SiO₂)

Fossil crinoid columnal in limestone

Crinoidea indet.; calcitic ossicle (CaCO₃)

Quartz fragment

Quartz, silicon dioxide (SiO₂)

Garnet

Almandine (Fe3Al2(SiO4)3)

Likely banded gneiss

Quartz–feldspar–mica gneiss (tentative visual identification)

Likely flint pebble (possibly a worked flint fragment)

Microcrystalline quartz (chalcedony), SiO₂; commonly called flint

Amphibolite

Hornblende amphibolite; chiefly hornblende and plagioclase feldspar

Tumbled quartz-rich stone, possibly quartzite

Quartzite (mostly SiO₂), possibly pale jasper or chalcedony

Milky quartz

Quartz, silicon dioxide (SiO₂)

Petrified wood

Silicified wood; commonly quartz/chalcedony (SiO₂) replacing organic tissue

Milky quartz

Quartz (silicon dioxide, SiO₂)

Likely quartz-rich pebbles

Quartz (SiO₂), possibly milky quartz or quartzite; identification is uncertain from the blurry image

Zebra marble

Banded calcite marble, commonly called zebra marble; chiefly calcite (CaCO₃), sometimes with dolomite and dark silicate or carbonaceous minerals

Milky quartz

Quartz (silicon dioxide, SiO₂)

Milky Quartz

Silicon Dioxide (SiO2)

Likely biotite mica schist

Mica schist, chiefly biotite (K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂) with quartz and feldspar

Unakite

Epidotized Granite

Weathered iron-rich metamorphic rock, likely banded ironstone or quartzite

Ferruginous quartzite/itabirite; mainly quartz (SiO₂) with iron oxides such as hematite and goethite

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Sandstone

Arenite

Tumbled white stone beads, likely marble or quartz

Undetermined; possibly marble (recrystallized calcite, CaCO₃) or milky quartz (SiO₂)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz geode or quartz-bearing rock

Quartz (SiO₂), likely in a chalcedony- or basalt-hosted cavity

Milky quartz

Quartz (silicon dioxide, SiO₂)

Schist

Mica Schist (primarily consisting of muscovite, biotite, and quartz)