Organic Material (Likely A Fruit Or Berry)

Chert (River Pebble)

Microcrystalline silica (SiO2)

Chert

Chert (SiO2)

Milky quartz with dark host-rock inclusions

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

Likely basalt with a pale mineral-filled vesicle

Vesicular basalt, probably containing calcite or zeolite (uncertain from image)

Iron-rich chert or jasper pebble

Microcrystalline quartz (SiO₂), colored by iron oxides

Weathered granitic rock

Granitoid, likely biotite granite or granodiorite

Chert (variations include Flint)

Chert (SiO2)

Amber

Succinite (C10H16O)

Limestone

Sedimentary rock composed mainly of calcite (CaCO3)

Quartz / Limestone Gravel

SiO2 (Silicon Dioxide) and CaCO3 (Calcium Carbonate)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Jasper/Black Chert)

Silicon Dioxide (SiO2)

Quartz-rich sandstone or quartzite cobble

Quartz arenite; possibly weakly metamorphosed quartzite (SiO₂-dominant)

Chert (and Chalcedony)

Silicon Dioxide (SiO2)

Rounded brown pebble, likely weathered sandstone or iron-stained quartzite

Probable quartz-rich sandstone (SiO₂-dominated); exact identification requires testing

Sandstone (likely Ferruginous)

Arenite with Iron Oxide cement

Chert (often called Flint for darker varieties)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Chert (Jasper)

Silicon Dioxide (SiO2)

Small polished brown stone

Indeterminate; possibly tumbled jasper, brown agate, or another iron-stained silicate

Rounded granite pebble

Granite, predominantly quartz, feldspar, and mica

Quartz-rich breccia or vein quartz with iron staining

Microcrystalline to crystalline SiO₂, likely quartz with iron oxides/hydroxides and altered host rock

Chert (Gravel)

Microcrystalline silica (SiO2)

Chert (Flint)

Chert (Microcrystalline or cryptocrystalline Quartz - SiO2)

Chert (varieties include Flint and Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Yellow/Tan)

Microcrystalline Quartz (SiO2)

Water and Silt (Sedimentary Environment)

Suspended Sediment / H2O (dihydrogen monoxide)

Black Marble

Recrystallized Calcite (CaCO3)

Travertine

Terrestrial Sedimentary Limestone (CaCO3)

Chert (specifically Flint or Common Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Crinoid Stem Fossil (Indian Bead)

Crinoid ossicle (Echinodermata)

Vesicular basalt (likely weathered scoria)

Basaltic volcanic rock; chiefly plagioclase, clinopyroxene, and olivine with vesicles

Coarse-grained granite or granitic pegmatite

Granite; primarily quartz (SiO₂), feldspar, and mica/amphibole

Fossil brachiopod shell

Likely spiriferid or strophomenid brachiopod; calcium carbonate (primarily calcite)

Sandstone (Quartz Arenite)

Sandstone (SiO2 with possible mineral cements)

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

Chert (Black Chert/Flint)

Silicon Dioxide (SiO2)

Mixed pebble collection, including likely flint, quartzite, and fossil material

Varied silicate rocks; visible specimen may include chert (microcrystalline SiO₂), quartzite, and a possible fossil

Weathered quartz-rich stone, possibly fossiliferous limestone

Indeterminate; likely calcite-rich limestone (CaCO₃) or weathered quartz-bearing rock

Granite Pebble

Granite (Phaneritic intrusive igneous rock consisting of Quartz, Alkali Feldspar, and Plagioclase)

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Weathered chert or jasper nodule

Microcrystalline quartz (SiO₂), likely chalcedony/jasper with iron-oxide staining

Rounded quartz-rich beach pebble

Likely milky quartz or quartzite (SiO₂)