Mineral (Biogenic Replacement)

Chert (Jasper/Chalcedony variety)

Silicon Dioxide (SiO2)

Fossilized Sea Urchin (Echinoid)

Echinoidea (Class); commonly Clypeasteroida for sand dollar types

Polished tiger-eye jasper / iron-rich jasper

Quartz-rich jasper (microcrystalline SiO₂) with iron oxides, likely hematite/goethite and magnetite

Galena

Lead(II) sulfide (PbS)

Chert / Flint Pebble

Microcrystalline Silica (SiO2)

Likely iron-rich sulfide ore (possibly sphalerite with oxidized iron minerals)

Appearance may indicate sphalerite (ZnS) with limonite/goethite staining; identification from the image is uncertain.

Tumbled/polished purple fluorite (probable)

Fluorite, calcium fluoride (CaF₂)

Likely galena-bearing sulfide ore

Galena (lead sulfide, PbS), possibly with sphalerite and quartz/calcite gangue

Likely galena-bearing ore or metallic sulfide specimen

Probably galena (PbS), possibly mixed with pyrite or other sulfides

Weathered quartz-rich pebble, possibly jasper or chert

Microcrystalline quartz (SiO₂), with iron-oxide staining and possible clay/mineral inclusions

Galena (probable)

Galena, lead sulfide (PbS)

Grey Chalcedony (Tumbled)

Chalcedony (SiO2)

Likely galena-bearing ore

Galena (PbS), possibly mixed with quartz or carbonate gangue

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Red Tiger's Eye

SiO2 (Silicon Dioxide) - Pseudomorph of Quartz after Crocidolite

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Polished fossil coral

Fossilized colonial coral, commonly tabulate or rugose coral; calcite (CaCO₃) replacement

Chert (Tripolitic Chert / Flint Nodules)

Microcrystalline Quartz (SiO2)

Iron-rich chert or weathered ironstone

Chert (microcrystalline quartz, SiO₂) with iron-oxide minerals

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Polished pale-green stone, likely serpentine or jade

Serpentine-group mineral (commonly antigorite/lizardite), or possibly nephrite jade (tremolite–actinolite amphibole)

Tumbled green fluorite (probable)

Fluorite, calcium fluoride (CaF₂)

Likely galena-bearing ore or graphite-rich sulfide fragment

Indeterminate; possibly galena (PbS) with quartz, or graphite-rich schist

Banded fluorite (likely)

Fluorite, calcium fluoride (CaF₂)

Likely galena-bearing rock

Galena, lead sulfide (PbS), in a dark host rock

Polished jasper pebble

Microcrystalline quartz (chalcedony), usually with iron-oxide impurities

Chalcedony (likely iron-stained agate)

Microcrystalline quartz, SiO₂ (chalcedony/agate)

Fossilized Shark Tooth

Elasmobranchii gen. indet.

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Chert / Flint

Microcrystalline Quartz (SiO2)

Orthoceratid Fossil in Limestone

Orthoceras (extinct genus of Nautiloid Cephalopod)

Petrified Wood

Silicified Wood (SiO2)

Fossil coral pebble and banded stone

Likely fossilized tabulate or rugose coral (left); right specimen may be silicified coral or weathered limestone

Petrified Wood

Silicified Wood (SiO2)

Fossil scallop shell

Bivalve mollusk shell, likely family Pectinidae; primarily calcite (CaCO₃)

Ammonite Fossil in Matrix

Ammonoidea subclass (e.g., Arietites or similar genera)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint Nodules)

Chert (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Chert (Lithic flake / Arrowhead fragment)

Microcrystalline Quartz (SiO2)

Sea Urchin Fossil

Echinoidea (test/fossil)

Petrified Wood

Silicified Wood (SiO2)