Anthropogenic (Man Made Material Processed By Nature)

Shale (sub-type: Carbonaceous Shale)

Lutaceous Sedimentary Rock

Hag Stone (Flint with natural hole)

Silicon Dioxide (SiO2) - Nodular Chert / Flint

Peridot

Olivine (specifically, the gem-quality variety forsterite, (Mg,Fe)2SiO4)

Phyllite (possibly low-grade greenish slate)

Foliated metamorphic rock composed mainly of very fine-grained quartz, mica, and chlorite; approximate composition varies and has no single fixed chemical formula

Orgonite Pyramid (containing Amethyst and mixed minerals)

Silicon Dioxide (SiO2) in synthetic resin

Yellow Quartz (Citrine/Yellow Jasper mix)

Silicon Dioxide (SiO2) with iron oxide inclusions

Mica schist (possibly garnet–mica schist)

Muscovite–biotite schist; chiefly quartz, feldspar, muscovite, and biotite

Unknown Dark Stone

Unknown

Vesicular basalt (weathered volcanic rock)

Basalt, chiefly plagioclase feldspar, clinopyroxene, and possibly olivine/iron oxides

Likely vertebra fossil or bone fragment

Indeterminate fossilized vertebra; mineralized hydroxyapatite, commonly Ca₅(PO₄)₃(OH)

Weathered limestone or calcitic fossil/reef fragment

Calcite-rich limestone (CaCO₃), possibly fossiliferous limestone

Polished blue chalcedony or glass-like quartz specimen

Chalcedony (microcrystalline SiO₂), possibly treated or synthetic; exact identification requires testing

Carnelian (red chalcedony), possibly red agate or jasper

Chalcedony, a microcrystalline variety of quartz; silicon dioxide (SiO₂), commonly colored red-orange by iron oxides. The specimen may include opaque jasper or agate zones.

Quartzite

Quartzite (SiO2)

Yellow-orange faceted gemstone, likely citrine or yellow topaz

Citrine: quartz, SiO₂; yellow topaz: Al₂SiO₄(F,OH)₂

Granite

Granite (Felsic intrusive igneous rock)

Pearl (Biogenic Mineraloid)

Calcium carbonate (CaCO3) primarily as Aragonite

Jasper Pendant

Chalcedony (Quartz) - SiO2

Sapphire

Corundum (Al2O3)

Asphalt (Bituminous Rock)

Natural bitumen or Bituminous limestone/sandstone

Carnelian/chalcedony rough

Microcrystalline quartz (SiO₂), iron-oxide-colored chalcedony

Diamond

Diamond (C)

Milky quartz vein rock

Quartz, silicon dioxide (SiO₂), likely with iron-oxide staining and minor mica or sulfide minerals

Purple fluorite-bearing matrix specimen

Fluorite (calcium fluoride, CaF₂), likely with quartz and host-rock minerals

Iron sulfide-rich ore, possibly pyrite-bearing gossan

Likely pyrite (FeS₂) with iron oxides/hydroxides and host rock; exact identification requires testing

Fossiliferous limestone, possibly containing a brachiopod or bivalve fossil

Calcite-rich limestone (CaCO₃), with an apparent shell impression or shell fragment

Red cabochon gemstone, likely carnelian or dyed chalcedony

Chalcedony (microcrystalline quartz), SiO₂; exact identification requires testing

Sandstone

Quartz Arenite (a type of sandstone composed of more than 90% quartz)

Raw gold nugget or gold-bearing quartz

Native gold (Au), possibly with quartz (SiO₂) and iron-oxide staining

Coral Fossil (Fossilized Coral)

Hexagonaria or similar rugose/tabulate coral fossil (Calcium Carbonate, CaCO3)

Cockle Shell (Fossil or Recent)

Class Bivalvia, Family Cardiidae (e.g., Cerastoderma edule for common cockle)

Milky Quartz

Silicon Dioxide (SiO2)

Granite Boulder

Felsic Intrusive Igneous Rock

Worn quartz-rich pebble, likely chert or quartzite

Microcrystalline quartz (SiO₂), possibly quartzite

Rounded pebble, likely quartz-rich sandstone or chert

Indeterminate lithic clast; possibly quartz arenite or microcrystalline quartz (SiO₂)

Milky Quartz

Silicon Dioxide (SiO2)

Polished blue agate/geode slice

Chalcedony (microcrystalline quartz, SiO₂), likely dyed blue

Likely dark rounded pebbles

Indeterminate; possibly basalt or a dark mafic mineral such as hornblende/biotite

Slate

Foliated Metamorphic Slate

Basalt

Extrusive Igneous Rock

Chert (Flint)

Chert (microcrystalline quartz)

Tumbled turquoise-like stone

Likely turquoise, hydrated copper aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O