Anthropogenic (Man Made Material Processed By Nature)

Vesicular basalt (likely weathered scoria)

Basaltic volcanic rock; chiefly plagioclase, clinopyroxene, and olivine with vesicles

Tumbled green gemstone, likely dyed howlite or serpentine

Most consistent with dyed howlite (Ca2B5SiO9(OH)5); exact identification requires testing

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Citrine

Citrine (Silicon Dioxide, SiO2)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Citrine Quartz Sphere

Silicon Dioxide (SiO2)

Emerald

Beryl (Be3Al2(SiO3)6) with trace Chromium/Vanadium

Quartz-rich pegmatitic rock (likely quartz–feldspar–mica specimen)

Granitic pegmatite; mainly quartz (SiO₂), feldspar, and dark mica/amphibole

Gray chalcedony (microcrystalline quartz)

Chalcedony, SiO₂; likely common gray/blue-gray variety

Iron Meteorite

Siderite (Iron-Nickel Meteorite)

Chert (often called Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Diamond

Carbon (C)

Smooth gray river pebble

Likely fine-grained sandstone or siltstone; exact identification requires a fresh surface and tests

Likely weathered metallic mineral or slag fragment

Indeterminate; possibly iron-rich sulfide/oxide material or industrial slag

Coal

Combustible sedimentary rock

Tumbled green-and-white stone, likely serpentine

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and carbonate veins

Orange fire opal jewelry

Precious opal, hydrated amorphous silica (SiO₂·nH₂O)

Yellow Citrine Quartz

Silicon Dioxide (SiO₂)

Cubic Zirconia (or possibly Diamond)

Zirconium dioxide (or Carbon)

Banded Chert

Silicon Dioxide (SiO2)

Flint / Chert

Silicon dioxide (SiO2)

Flint

Chert (a form of cryptocrystalline quartz, chemical formula SiO₂)

Milky Quartz

Silicon Dioxide (SiO2)

Green Quartz (Prasiolite)

Crystalline Silicon Dioxide (SiO2)

Pink-and-white quartz-rich rock, likely rose quartz or quartzite

Quartz (SiO₂), possibly rose-quartz-bearing quartzite; minor iron-oxide staining

Dyed pink agate slice

Agate (microcrystalline quartz, SiO₂), commonly chalcedony with artificial dye

Tumbled Stone

Silicon dioxide / Various silicates

Ferruginous Slag (Iron Smelting Byproduct)

Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)

Milky Quartz Geode / Chalcedony Nodule

Quartz (Silicon Dioxide - SiO2)

Sandstone

Arenite (predominantly SiO2)

Sandstone

Arenite (SiO2 principal)

Sandstone

Arenite (Siliclastic sedimentary rock)

Sandstone

Arenite (SiO2 based)

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Weathered iron-rich rock, possibly limonite-bearing sandstone

Limonite/goethite mixture, approximately hydrated iron oxides (FeO(OH)·nH₂O), possibly coating sandstone or ironstone

Rhyolite or jasper-bearing volcanic rock

Rhyolite, likely altered and silicified; red coloration may come from hematite

Granite Gravel / Crushed Granite

Plutonic Felsic Igneous Rock

Rhinestone (or glass crystal)

Silicon dioxide (if glass) / Various

Yellow Sapphire (Raw)

Corundum (Al2O3)

Dyed Blue Agate

Silicon Dioxide (SiO2) with artificial pigment

Brown chalcedony (likely carnelian/agate)

Cryptocrystalline quartz, SiO₂; iron-bearing chalcedony