Mineral (Sedimentary Context)

Mixed gravelly conglomeratic road aggregate

Polymictic clast-supported conglomerate or fill; composition varies, commonly quartz, feldspar, basalt, and weathered rock fragments

Nickel coin (U.S. currency)

Cupronickel (75% Copper, 25% Nickel alloy)

Quartz-rich hydrothermal vein rock, possibly quartzite

Mostly SiO₂ (quartz), with probable iron oxides and minor sulfides

Yellow Jasper

Chalcedony (SiO2) with iron oxide inclusions

Unidentified Rock Fragment

Unknown

Weathered quartz-rich rock, possibly chert or quartzite

Likely microcrystalline quartz (SiO₂), but exact identification is uncertain from the photograph

Rounded sandstone pebble

Clastic sandstone, predominantly quartz (SiO₂) grains in a cementing matrix

Seashell (Cone Snail Shell)

Conus sp. (Calcium Carbonate, CaCO3)

Flint (chert)

Microcrystalline quartz (SiO₂), variety of chert

Quartz (Bull Quartz)

Silicon Dioxide (SiO2)

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Ferruginous Sandstone Concretion (Ironstone Phosphorite)

Ferruginous Sandstone (variable Fe-oxide/hydroxide composition)

Hag Stone

Perforated Sedimentary Rock (typically Sandstone or Siltstone)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Fossil shell fragment (likely bivalve)

Bivalvia indeterminate; shell material chiefly aragonite or calcite (CaCO₃)

Sea Shell (Fighting Conch Fragment)

Calcium Carbonate (CaCO3) - Strombus alatus fragment

Polymictic conglomerate

Lithified polymictic conglomerate; clasts likely quartzite, granite, and volcanic rock in a dark matrix

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Polished green aventurine (likely)

Quartz, SiO₂, with green mica or other mineral inclusions; the photo alone cannot confirm the exact stone.

Sandstone (Ferruginous Concretion)

Ferruginous Sandstone Concretion / SiO2 with Fe2O3 cement

Quartz Geode

Silicon Dioxide (SiO2)

Ironstone Concretion

Limonitic/Hematitic Concretion

Chert (Arrowhead/Projectile Point)

Microcrystalline Quartz (SiO2)

Pyrite

Pyrite (FeS₂)

Unidentified dark, flat specimen

Indeterminate; image resolution is insufficient for mineral identification

Rose Quartz

Silicon Dioxide (SiO2) containing trace amounts of titanium, iron, or manganese

Red Sandstone

Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)

Sulfidic Mudstone with Pyrite/Goethite

Sulfidic Siltstone/Mudstone (FeS2)

Bivalve Fossil (Clam)

Class Bivalvia (e.g., Mercenaria or similar genus), composed of CaCO3 (Aragonite/Calcite)

Exposed aggregate concrete (stone-chip surface)

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

Hematite

Iron(III) oxide (Fe2O3)

Red Jasper

Opaque microcrystalline Quartz (SiO2 with Fe2O3 inclusions)

Metal Chain (Likely Steel or a Steel Alloy)

Steel (primarily iron and carbon); specific alloy unknown

Leopard Skin Jasper

SiO2 (Microcrystalline Quartz with inclusions)

Fossiliferous Limestone with Crinoid Stem fragment

Calcite (CaCO3) containing Crinoidea fossils

Sandstone Concretion

Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)

Red obsidian (likely mahogany obsidian)

Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), commonly with iron-oxide inclusions

Flint (chert), likely a worked stone flake

Microcrystalline quartz (SiO₂); cryptocrystalline variety of quartz

Red Jasper

Silicon Dioxide (SiO2) with Iron inclusions

Yellow Jasper

Silicon Dioxide (SiO2)

Kidney Stone

Calcium Oxalate (CaC2O4), Uric Acid, or Struvite

Iron-stained chert (flint) nodule

Microcrystalline quartz (SiO₂), with iron-oxide staining