Mineral, Specifically A Rock Fragment

Shale fragment

Shale (clay mineral rich sedimentary rock)

Unidentified weathered mineral/rock fragment

Indeterminate; likely a weathered iron-rich silicate or sulfide-bearing specimen

Sandstone (specifically Cross-bedded Sandstone)

Arenite (composed primarily of SiO2)

Basalt with Chert/Obsidian blade

Aphanitic Mafic Igneous Rock (Basalt) with Microcrystalline Silica (Chert)

Weathered brown rock fragment

Indeterminate; possibly weathered granite, gneiss, or iron-stained quartz-rich rock

Red Painted Rock

Artificial Coated Lithic Fragment

Chert (specifically a weathered Chert nodule or fragment)

Chert; Microcrystalline or Cryptocrystalline Quartz (SiO2)

Leopard Skin Jasper

Orbicular Jasper (Silicon Dioxide, SiO2)

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Chrysotile Asbestos

Mg3Si2O5(OH)4

Granite Pebble

Granite (composed primarily of Quartz, Feldspar, and Mica)

Quartz

Silicon Dioxide (SiO2)

Seashell Fragment

Calcium Carbonate (CaCO3) in the form of Aragonite or Calcite

River Pebble

Weathered Sedimentary Rock Fragment

Quartz (Gravel Fragment)

Silicon Dioxide (SiO2)

Unidentifiable Rock Fragment

Unknown Rock Fragment

Undetermined

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Unidentified dark pebble

Undetermined; possibly polished basalt, chert, or iron-rich stone

Small brown mineral fragment, possibly quartz/chert

Uncertain; likely microcrystalline quartz (SiO₂) or a weathered silicate rock

Lake Superior Agate

Chalcedony (SiO2 with iron impurities)

Quartz Druse on Basalt Matrix

Silicon Dioxide (SiO2)

Uncertain small pale mineral fragment

Indeterminate; possibly calcite or a light-colored feldspar fragment

Quartz-veined Granite or Gneiss Pebble

Silicate-rich metamorphic rock fragment

Fossilized Echinoid Fragment (Calycinal/Boss Fossil)

Echinodermata fossil fragment

Sandstone (Ferruginous)

Arenite with Iron Oxide cement (SiO2 + Fe2O3)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Rock Fragment with Calcite/Quartz Vein

Polymictic Rock Fragment (SiO2 / CaCO3)

Weathered quartz-rich rock fragment

Likely quartz-bearing feldspathic rock; exact identification requires testing

Weathered granitic rock fragment

Likely granite or granodiorite; quartz–feldspar–mica aggregate

Chalcedony (Agate/Quartz)

Silicon Dioxide (SiO2)

Quartz / Common Opal Transition

Silicon Dioxide (SiO2)

Unidentified weathered rock fragments

Likely mixed quartz- and feldspar-bearing silicate material; exact identification requires testing

Sandstone (Ferruginous)

Arenite with Iron Oxide (Limonite/Hematite) coating

Small dark metallic-looking rock fragment

Undetermined; possibly iron oxide-rich material or a metallic mineral

Limestone (specifically Fossiliferous or Crinoidal Limestone)

Calcium Carbonate (CaCO3) - Calcite Rock

Pebble / Gravel Fragment

Clastic Rock Fragment

Crushed Stone Ballast

Crushed Limestone or Granite Aggregate

Labradorite

(Ca, Na)(Al, Si)4O8

Quartz Fragment

Silicon Dioxide (SiO2)

Chalcedony Geode Fragment

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Tumbled brecciated jasper

Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions