Organic (Pseudo Geological)

Fossil bivalve shell

Ribbed pectinid or related bivalve; originally calcite/aragonite (CaCO₃), likely partially mineralized

Fossilized Gastropod (Snail)

Class Gastropoda (internal mold or 'steinkern')

Fossil mammalian skull

Fossilized vertebrate bone; exact taxon cannot be determined from the image

Chert (with Quartz vein)

Chert (Silicon Dioxide, SiO2)

Amber (Copal)

Organic gemstone, fossilized tree resin (often immature amber or copal)

Coal (likely bituminous coal)

Bituminous coal; predominantly carbon with organic macerals and minor clay/pyrite

Opalite

Synthetic Opalised Glass

Petrified Wood

Silicified Wood (SiO2)

Graphite

Graphite (Carbon, C)

Petrified Wood

Silicified wood (Quartz / Chalcedonized wood, SiO2)

Amber (likely raw amber)

Fossilized tree resin; organic mineraloid, commonly containing succinite (not a true mineral)

Black Chert (Flint)

Microcrystalline Quartz (SiO2)

Pyrite

Iron Pyrite (FeS2)

Polished yellow calcite

Calcite (calcium carbonate, CaCO₃)

Basaltic Tuff / Volcanic Breccia

Pyroclastic Breccia / Lithic Tuff

Petrified Wood

Silicified Wood (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Small yellow-orange mineral fragment, likely amber or iron-stained quartz

Possibly amber (fossilized resin; organic mineraloid) or quartz (SiO₂)

Red Sandstone with Reduction Spot

Quartzose Sandstone with a Leach/Reduction Spot

Petrified Wood

Silicified Wood (primarily quartz/chalcedony replacing organic wood structures, SiO2)

Sandstone with Trace Fossils

Quartz Arenite with Bioturbation (Trace Fossils)

Petrified Wood

Silicified Wood (primarily quartz/chalcedony replacing organic wood structure, SiO2)

Quartz Geode

Silicon Dioxide (SiO2)

Fossilized bone, likely a large vertebrate limb or rib fragment

Petrified bone; exact taxon indeterminate from the image

Tahitian black pearl strand

Cultured pearl; aragonite (CaCO₃) nacre

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)

Dendritic Opal (Common Opal)

Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions

Beach sandstone or cemented beachrock fragment

Lithified carbonate- or silica-rich sand; commonly calcarenite or quartz sandstone

Wood Beads (Palmwood/Ebony)

Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.

Likely anthracite coal fragments

Anthracite; predominantly carbon (C), with minor mineral ash

Polished jasper, likely orbicular or brecciated jasper

Jasper: microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides and other inclusions

Fossilized Wood (Petrified Wood)

Silicified Wood (primarily quartz/chalcedony replacing organic matter)

Fossilized Horn Coral

Rugosa (Tetracoralla)

Zebra Marble

Metamorphosed Alabaster/Limestone (CaCO3)

Pyrite

Pyrite (Iron Disulfide), FeS2

Banded Chert / Banded Jasper (likely a variety of Chert/Chalcedony)

Chert (microcrystalline quartz)

Polished amber-like organic gemstone

Likely amber (fossilized plant resin), possibly copal or brown chalcedony; exact identification requires testing

Cave (botryoidal) aragonite or calcite specimen

Aragonite (CaCO₃), possibly mixed with calcite and iron-oxide inclusions

Ambergris

Physeter macrocephalus excreta (Ambergris)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Anthracite Coal

Anthracite (Metamorphic/High-grade Sedimentary Coal)

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)