Sedimentary Or Metamorphic (Base Substrate)

Amethyst and Gravel Collection

Amethyst (Silicon Dioxide, SiO2)

Granite Gneiss

Granitoid Gneiss

Quartzite River Rock

Quartzite (primarily SiO2)

Shungite

Non-crystalline carbon (allotrope of carbon)

Gneiss

Gneiss (Foliated Metamorphic Rock)

Weathered mica-rich rock (tentative identification)

Possibly mica schist or phyllite; exact identification requires closer examination

Gneiss

Gneiss (High-Grade Metamorphic Rock)

Biotite Schist

Metamorphic rock rich in biotite mica

Small white mineral fragment

Likely quartz (SiO₂), possibly calcite (CaCO₃)

Sandstone with Liesegang Rings

Quartzose Sandstone with Iron Oxide Precipitation

Gneiss

Gneiss (SiO2-rich metamorphic rock)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Quartzite Pebbles with Quartz Veining

SiO2 (Silicon Dioxide with country rock matrix)

Gneiss

Gneiss (Foliated Metamorphic Rock)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Carnelian

SiO2 (Silicon Dioxide with Iron Oxide impurities)

Gneiss (Metamorphosed Granitic Rock)

Gneiss (composed mainly of quartz, feldspar, biotite, and/or hornblende)

Gneiss

Gneiss

Banded Gneiss

Gneiss (Felsic to Mafic Metamorphic Rock)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Mixed collection of common river stones

Varied lithologies, visibly including quartz-rich rock, dark mafic rock, sandstone, and purple quartz-bearing material

Likely pyrite-bearing rock

Pyrite (FeS₂), possibly disseminated in a host rock

Pyrite-bearing rock (likely pyrite-rich ore)

Pyrite, FeS₂, in a fine-grained host rock

Chalcedony (Agate) Pebble

Silicon Dioxide (SiO2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Clear quartz crystals

Quartz (silicon dioxide, SiO₂)

Epidote with Quartz Vein

Epidote-bearing metamorphic rock with quartz (Ca2(Al,Fe)3(SiO4)3(OH))

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Gneiss

Gneiss (Metamorphic Rock)

Muscovite Mica

KAl2(AlSi3O10)(F,OH)2

Blue Kyanite in Schist

Al2SiO5 in Mica Schist

Quartz-rich limestone or calcitic marble

Calcite (CaCO₃), possibly with quartz (SiO₂)

Weathered foliated metamorphic rock, likely schist or gneiss

Mica schist to gneiss; commonly quartz + feldspar + biotite/muscovite

Likely biotite-rich schist

Mica schist, composed chiefly of biotite and quartz; exact identification is uncertain from the image.

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite

Gneiss (specifically a Hornblende Gneiss or Micaceous Gneiss)

Gneiss (metamorphic rock composed primarily of quartz, feldspar, and mafic minerals)

Small weathered mineral/rock fragment

Indeterminate; possibly quartz-bearing feldspathic rock or calcite-rich specimen

Gneiss (with Granite/Pegmatite Vein)

Foliated Metamorphic Rock (Quartz-Feldspar Gneiss)

Sandstone (Arkose)

Arkose Sandstone (principally SiO2 with Feldspar)

Gneiss

High-grade metamorphic rock (Gneiss)