Mineraloid (Human Made Geological Specimen)

Blue slag glass or dyed glass-like industrial material

Amorphous silicate glass; likely copper-bearing blue slag, but possibly colored man-made glass

Jasper / Flint / Chert

Microcrystalline Quartz (SiO2)

Diamond-encrusted microphone-shaped pendant

Diamond (natural or synthetic) set in gold-colored metal; exact stones and metal cannot be confirmed visually

Tumbled quartz (likely milky or rose quartz)

Quartz, silicon dioxide (SiO₂)

Green glassy gemstone-like specimen

Likely synthetic glass or treated quartz; exact identification requires testing

Chert

Microcrystalline quartz (SiO2)

Chert / Flint

Silicon Dioxide (SiO2)

Rounded graywacke or sandstone cobble

Lithified clastic sandstone; likely quartz–feldspar–lithic grain aggregate in a silica or calcite matrix

Tumbled cream-colored stone, possibly calcite or quartz

Indeterminate from image; likely calcite (CaCO₃) or milky quartz (SiO₂)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (often called Flint)

Chert (SiO2)

Tumbled chalcedony pendant (likely agate)

Chalcedony, microcrystalline quartz (SiO₂); the pale bands suggest agate

Polished pink-and-gray stone, possibly granite or rhyolite

Probable felsic igneous rock; likely quartz–feldspar–mica aggregate, but exact identification is uncertain from the image

Polished black volcanic rock, likely basalt or basaltic scoria

Basalt (fine-grained mafic silicate rock; commonly plagioclase, pyroxene, and iron oxides)

Tumbled jasper or quartz-rich chert

Microcrystalline quartz (SiO₂), likely jasper/chert with iron-oxide staining

Tumbled white quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Chert (with nodule)

Microcrystalline Quartz (SiO2)

Chert (Black Flint)

Silicon Dioxide (SiO2)

Tumbled carnelian agate

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

Spherical sandstone concretion

Sandstone concretion, commonly quartz-rich arenite cemented by calcite, silica, or iron oxides

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Brown Chert

Microcrystalline Quartz (SiO2)

Polished yellow-brown quartzite or jasper

Quartz-rich quartzite; possibly iron-stained jasper (microcrystalline SiO₂)

Weathered pegmatite or feldspar-rich granite fragment

Granitic pegmatite, composed mainly of potassium feldspar and quartz, with minor mica; exact identification is uncertain from the photograph

Petrified Wood

Silicified Wood (primarily SiO2)

Tumbled limestone or calcitic marble

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃)

Tumbled dark stone, possibly hematite or polished basalt

Uncertain; likely hematite (Fe₂O₃) or a polished mafic rock

Drill core of probable granite or granodiorite

Crystalline quartz–feldspar–mica rock; exact composition cannot be confirmed from the photograph

Pyrite in Quartz (Drill Core)

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2) inclusions

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Kidney Stone (Calcium Oxalate / Uric Acid)

Calcium Oxalate Monohydrate (Whewellite) / Calcium Oxalate Dihydrate (Weddellite)

Chert (Flint)

Chert (SiO2)

Crescent Pebble

Weathered Quartzite or Sandstone Fragment

Angel Aura Quartz (Treated Clear Quartz)

Silicon Dioxide (SiO2) coated with Vaporized Silver and Platinum

Tumbled quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Polished rainbow jasper (likely ocean/imperial jasper)

Microcrystalline quartz (SiO₂) with iron oxides and varied silicate inclusions

Tumbled quartz pebble

Quartz (SiO₂), likely milky or iron-stained quartz

Tumbled yellow-orange quartz

Quartz, silicon dioxide (SiO₂), likely iron-stained milky quartz or citrine-like quartz

Polished fossil-bearing limestone pebble

Bioclastic limestone, chiefly calcite (CaCO₃), possibly containing a small shell or coral fragment

Fulgurite

Liesegang (Fulgurite)

Polished jasper or jasper-rich breccia

Microcrystalline quartz (SiO₂), commonly with iron oxides and other silicates

Vesicular basalt (possibly slag-contaminated)

Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals