Mineral (Biogenic Replacement)

Fossilized Coral

Rugose Coral / Hexagonaria (Fossilized calcium carbonate)

Fossil oyster shell

Fossilized bivalve, likely an oyster (family Ostreidae); exact genus and age are indeterminable from the image

Fossilized bivalve shell fragment

Fossil Mollusca, likely a pectinid or related bivalve; exact identification requires the other shell half and locality

Pyrite (Fool's Gold) in Matrix

Iron Disulfide (FeS2)

Chalcedony (Chert/Flint)

Silicon Dioxide (SiO2)

Fossil shell fragment (likely brachiopod or bivalve)

Indeterminate fossilized carbonate shell; likely Brachiopoda or Bivalvia

Jasper

Silicon dioxide (SiO2) with impurities

Yellow Jasper

Tectosilicates (SiO2) with Goethite/Iron oxide inclusions

Fossilized ammonite

Ammonoidea (likely a ribbed Jurassic–Cretaceous ammonite), replaced mainly by calcite or silica

Fossilized Brachiopod

Phylum Brachiopoda

Fossilized Shark Tooth

Chondrichthyes (Class)

Crinoid Stem Fossil

Crinoid columnal (Echinodermata)

Fossilized Sand Tiger Shark Tooth

Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)

Fossil bivalve shell

Fossilized mollusk (Bivalvia), likely oyster or related species; exact genus requires locality and preparation

Lepidodendron Fossil (Scale Tree)

Lepidodendron sp.

Polished jasper pebble

Microcrystalline quartz (SiO₂), likely brecciated or orbicular jasper with iron-oxide impurities

Fossilized wood or plant fragment

Petrified wood (silicified fossil wood; commonly Araucarioxylon or related taxa)

Fossilized wood (petrified wood)

Silicified permineralized wood, commonly quartz (SiO₂) replacing or infilling woody tissue

Starfish Fossil

Asteroidea fossil

Fossil Shark Tooth

Chondrichthyes tooth fossil

Chert (likely jasper-bearing chert)

Microcrystalline quartz (SiO₂), with iron-oxide staining and possible chalcedony

Ferruginous Sandstone (Gozzanous)

SiO2 (Quartz) with FeO(OH) (Goethite) or Fe2O3 (Hematite) coating

Galena (lead sulfide)

Galena, PbS

Gastropod Fossil

Class Gastropoda (fossilized)

Sand Tiger Shark Tooth

Carcharias taurus

Galena (lead ore)

Galena, PbS (lead sulfide)

Weathered quartz-rich rock or fossil fragment

Indeterminate; likely quartz-bearing sandstone or siliceous fossil material

Weathered chert or siliceous limestone

Microcrystalline quartz (SiO₂), possibly with carbonate matrix

Sphalerite

Zinc Sulfide (Zn,Fe)S

Jasper

Silicon dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Fossilized Bone

Petrified Bone (Fluorapatite / Calcium Phosphate replacement)

Polished orbicular jasper (likely ocean jasper)

Silica-rich microcrystalline quartz/chalcedony with iron oxides and accessory minerals; SiO₂-dominant

Fossilized tooth, likely mammalian molar

Silicified or mineral-replaced mammalian tooth; exact taxon cannot be determined from the image

Fossil gastropod (snail shell)

Fossilized gastropod; original shell likely aragonite or calcite (CaCO₃), now partly mineral-replaced

Kidney Stone (Medical Specimen)

Calcium oxalate monohydrate (Whewellite) / CaC2O4·H2O

Fossilized bivalve shell

Fossil mollusk, likely an oyster or similar bivalve; original shell composed of calcium carbonate (aragonite/calcite)

Polished Ocean Jasper cabochon

Orbicular chalcedony (microcrystalline quartz, SiO₂), commonly with feldspar, zeolites, and iron-oxide inclusions

Polished ocean jasper (orbicular jasper), possibly rainforest jasper

Microcrystalline quartz/chalcedony (SiO₂) with iron-rich and other mineral inclusions

Green fluorite crystal

Fluorite (calcium fluoride, CaF₂)

Limonite with Galena

FeO(OH)·nH2O (Limonite) and PbS (Galena)

Fossil bone, possibly a large mammal long-bone fragment

Fossilized cortical bone; taxon indeterminate from the photograph