Igneous, Metamorphic, And Sedimentary (Mixed Assemblage)

Faceted Gemstones (Mixed)

Various (e.g., Corundum, Beryl, Quartz, or synthetic equivalents)

Banded metamorphic rock, likely gneiss or amphibolite

Composition uncertain; probable quartz–feldspar–amphibole assemblage

Mica Schist

Metamorphic rock primarily composed of quartz, micas, and feldspar

Banded metamorphic pebble, likely gneiss

Foliated gneiss; quartz–feldspar–mica assemblage

Weathered banded metamorphic rock, likely gneiss

Banded gneiss; commonly quartz–feldspar–mica assemblage

Educational Geologic Collection

Mixed Mineral and Rock Collection (Various compositions)

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Mixed tumbled rock and mineral collection

Varied specimens, including probable quartz varieties, jasper, agate, fluorite, rose quartz, amethyst, pyrite, calcite, and others

Migmatite

Migmatite (Mixed Rock)

Greenstone / Chert

Cryptocrystalline Quartz (SiO2) or Altered Basalt

Decorative mosaic cross containing mixed rock and glass fragments

Polychrome aggregate; likely quartz, feldspar, marble, granite, and assorted colored glass

Mixed River Pebbles

Clastic Sedimentary Alluvial Deposit / Polymictic Conglomerate Clasts

General Gravel (River Rock/River Stones)

Mixed Lithic Sediments (Conglomerate Clasts)

Limestone and Sandstone Assortment

Sedimentary Rock Assemblage

Mixed rock and mineral collection

Assorted geological specimens; individual species cannot be reliably identified from the image

Mixed mineral and rock collection

Predominantly quartz varieties, including amethyst, plus likely calcite, feldspar, mica, and miscellaneous polished stones

Eclogite

Eclogite (Omphacite + Pyrope-Almandine Garnet)

Banded gneiss pebble

Gneiss, typically quartz–feldspar–mica assemblage

River Pebbles and Quartz

Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)

Asphalt aggregate

Human-made bituminous asphalt containing crushed silicate rock aggregate

Weathered metamorphic rock, likely gneiss or schist

Indeterminate foliated silicate rock; commonly quartz–feldspar–mica assemblage

Foliated metamorphic rock, likely mica schist

Mica schist, mainly quartz–feldspar–mica assemblage

Weathered quartz-bearing metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica assemblage; exact mineral identification requires testing

Mixed Rock and Mineral Collection

Multiple geological specimens

Mixed river stones; foreground likely sandstone

Quartz-rich sandstone, with associated rounded quartzite/chert and other cobbles

Migmatite

Migmatite (Mixed metamorphic-igneous rock)

Quartz-rich rock or quartz specimen

Quartz (SiO₂), likely massive quartz or quartz-bearing host rock

Road-surface aggregate (crushed stone)

Unidentifiable mixed lithic aggregate; likely basaltic/andesitic fragments with feldspar, quartz, and weathered rock

Silver-colored mica schist

Muscovite–quartz schist, possibly with biotite

Mixed tumbled stones

Mixed aggregate of quartz, chalcedony, jasper, feldspar, and other common silicate minerals

Mixed rock and mineral collection

Multiple specimens; visible pieces may include quartz, calcite, agate/chalcedony, jasper, and dyed or coated materials

Likely pyrite-bearing metamorphic rock

Quartz–mica schist or gneiss with disseminated pyrite (FeS₂)

Arkosic Sandstone (or Conglomeritic Sandstone fragment)

Arkose (rich in feldspar)

Mixed rock and mineral specimen collection

Varied silicate, carbonate, and oxide minerals; individual identification is not possible from this group photograph

Tumbled gneiss (likely biotite gneiss)

Gneiss; quartz–feldspar–biotite assemblage

Mixed collection of natural stones

Several unidentified lithologies, likely including basalt, granite, quartzite, sandstone, and weathered metamorphic rocks

Stream cobbles and gravel

Unidentified mixed fluvial clasts; likely quartzite, sandstone, and igneous/metamorphic fragments

Aventurine (Green Quartz)

Silicon Dioxide (SiO2) with inclusions of Fuchsite (Mica)

Mixed rock and mineral specimen collection

Multiple species, likely quartz (SiO₂), calcite (CaCO₃), feldspar, chert, and assorted volcanic/sedimentary rocks

Greenstone pebble

Greenstone, typically metamorphosed basalt or andesite; often contains chlorite, epidote, and actinolite

Conglomeratic concrete or asphalt aggregate surface with dark bituminous chunks

Polymictic gravel aggregate; dark pieces likely bitumen/asphalt, not a natural rock

Tumbled quartz-rich stone, possibly milky quartz or calcite

Quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing