Metamorphic (Likely Gneiss Or Schist Based On Texture)

Granite Cobble / Gneiss (River Rock)

Granitic Gneiss / Felsic Igneous Rock

Quartzite Pebble

Quartzite (SiO2)

Porcelain (Kaolin-based)

Alumina silicate ceramic (composed primarily of Kaolinite: Al2Si2O5(OH)4)

Granite

Granite (a felsic intrusive igneous rock)

Rounded quartz-rich river pebble

Quartz-rich sandstone or quartzite; chiefly silicon dioxide (SiO₂)

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

Quartz Vein in Host Rock

Hydrothermal Quartz (SiO2) in Slates/Schists

Diorite

Phaneritic Intermediate Igneous Rock

Iron-rich quartzite or ferruginous metamorphic rock

Ferruginous quartzite, likely hematite/goethite-bearing quartzite; SiO₂ with Fe₂O₃/FeO(OH)

Limestone with Iron Inclusions

Calcium Carbonate (CaCO3) with Hematite/Limonite

Limestone (specifically Grainstone or Micrite)

Calcium Carbonate (CaCO3)

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly with iron-oxide staining and minor feldspar or mica

Epidote

Epidote (Ca2(Al, Fe)3(SiO4)3(OH))

Jasper

Silicon dioxide (SiO2)

Orange Quartzite (River Pebble)

Quartzite (SiO2 with iron oxide impurities)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Emerald in Matrix

Beryl (Be3Al2(SiO3)6) embedded in schist or pegmatite host rock

Basalt Porphyry

Porphyritic Basalt

Gravel (likely Basalt or Greywacke)

Basalt (Mafic volcanic rock)

Weathered sandstone or tuff fragment

Likely quartz-rich sandstone (SiO₂) or porous volcanic tuff; exact identification requires testing

Sandstone or Quartzite

Arenite (if sedimentary) / Quartzite (if metamorphic)

Cream Marble (Speckled)

Metamorphosed Limestone (mainly CaCO3)

Greenschist (or Serpentinite) with Quartz-Feldspar Vein

Metabasalt / Greenschist Facies Rock

Magnetite or Ironstone Nodule

Magnetite (Fe3O4) or Hematite-rich Sedimentary Nodule

Epidote

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

Quartz-veined Granite or Gneiss Pebble

Silicate-rich metamorphic rock fragment

Fuchsite

Chromium-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)

Ruby

Corundum (Al2O3:Cr)

Quartz (Smoky/Granular variety)

Silicon Dioxide (SiO2)

Basalt with Peridotite Xenolith

Mafic Igneous Rock with Peridotite Inclusion (Olivine-rich)

Pumice

Pumice (Amorphous volcanic glass)

Sand Tiger Shark Tooth Fossil

Carcharias taurus (fossilized tooth)

Milky quartz with dark host-rock inclusions

Quartz (SiO₂), likely in a granitic or metamorphic matrix

Tumbled carnelian agate with dark mineral inclusions

Carnelian, an orange variety of microcrystalline quartz (chalcedony), SiO₂; dark inclusions are likely iron oxides/hydroxides, possibly hematite, goethite, or a basaltic/matrix fragment

Tumbled milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz / Iron-Stained Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions/staining

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz (Milky or Citrine-tinted)

Silicon Dioxide (SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

White Quartz Pebble

Silicon Dioxide (SiO2)

Pink Granite

Felsic intrusive igneous rock (Granite)