Rock

Small dark rock fragment, possibly shale or slate

Undetermined fine-grained silicate rock; visual identification is inconclusive

Weathered granite boulder

Granite, a quartz–feldspar-rich intrusive igneous rock

Vesicular Basalt (Scoria)

Vesicular Basalt

Manhattan Schist

Manhattan Schist (Aluminous Metasedimentary Rock)

Decorative polished pebbles

Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt

Quartz-veined Sandstone Pebble

Quartzite-veined Arenite

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz with Limonite/Goethite staining)

Unakite

Epidotized Granite

Shale

Shale (Lutite)

Tiger Iron

Tiger Iron (Composition: SiO2, Fe2O3, Fe3O4)

Pink Quartzite

Quartzite (SiO2 with minor iron oxide impurities)

Shale

Fissile mudrock (composed primarily of clay minerals and quartz)

Vesicular Basalt (or Scoria)

Vesicular Basalt (Aphanitic-vesicular volcanic rock)

Unakite

Epidotized Granite

Gravel

Unconsolidated aggregate of mixed rock and mineral fragments

Gravel (mixed crushed stone)

Unidentified aggregate of crushed natural rock fragments

Rounded river pebble, likely sandstone or quartzite

Unidentified silicate-rich pebble; visual appearance is consistent with sandstone, but quartzite is also possible

Fossil-bearing limestone with a probable fossil shell

Fossiliferous limestone; the visible fossil may be a gastropod or other shelly fossil, but the image is not diagnostic enough for species identification.

Raw blue sodalite

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Sandstone or possibly a conglomerate

Arenite (if sandstone)

Granite

Felsic intrusive igneous rock

Not a geological specimen

N/A (man-made object)

Pumice

Pumice (Vesicular Rhyolite/Andesite)

Quartz in Matrix (possibly Basalt or Siltstone host)

Silicon Dioxide (SiO2) in Host Rock

Basalt

Aphanitic Mafic Igneous Rock

Quartz Veined Rock (Likely Graywacke or Quartzite)

Silicon Dioxide (SiO2) veins in Metasedimentary matrix

Mica-rich granite (likely weathered pegmatitic granite)

Granite, chiefly quartz (SiO₂), feldspar, and mica (muscovite and/or biotite)

Quartz–iron-oxide breccia or weathered quartz-bearing rock

Quartz (SiO₂) with limonite/goethite and possibly iron sulfides in a brecciated host

River Pebble (likely Quartzite or Chert)

Sedimentary Clast (Silicon Dioxide dominant)

Orbicular Jasper (Ocean Jasper)

Silicon Dioxide (SiO2) with various inclusions

Sandstone Cobble

Clastic Sedimentary (Sandstone)

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)

Chert / Chalcedony (likely carnelian or flint variety)

Silicon Dioxide (SiO2)

Glacial Cobble with Granite Inclusion

Porphyritic Basalt or Andesite containing Granitic Xenolith

Rounded granite cobble

Granite; predominantly quartz, alkali feldspar, plagioclase, and mica

Pegmatitic gneiss with a quartz–feldspar vein

Quartz–feldspar-rich gneiss, locally cut by a granitic pegmatite vein

Weathered granite or granitic gneiss

Felsic granitoid; primarily quartz, feldspar, and mica

Weathered quartz-rich rock, possibly vein quartz

Quartz-rich rock; predominantly silicon dioxide (SiO₂), exact rock type uncertain from the photograph

Basalt with Calcite Veins

Basalt (containing CaCO3 inclusions)

Mixed rock collection

Labeled specimens appear to include iron-rich rock, schist, basalt, serpentinite, and shale

Quartz (Druzy on Matrix)

Silicon Dioxide (SiO2)

Black Limestone with Calcite Veining

Bituminous Limestone (CaCO3 with Organic Carbon inclusions)