Anthropogenic (Man Made Material Processed By Nature)

Weathered quartz-rich metamorphic rock, possibly quartzite

Quartzite; predominantly quartz (SiO₂), with minor feldspar, mica, and iron-oxide staining

Water-worn basalt cobble

Basalt; chiefly plagioclase feldspar, pyroxene, and minor olivine/iron oxides

Weathered quartz-rich rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly iron-oxide stained

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, possibly granitic gneiss

Biotite-rich granite or granitic gneiss

Granite; quartz–feldspar–biotite assemblage

Weathered granite or granitic gneiss

Granite; primarily quartz, feldspar, and mica (possibly metamorphosed to gneiss)

Fossiliferous limestone

Bioclastic carbonate rock, primarily calcite (CaCO₃)

Rounded quartz-rich beach pebble

Likely milky quartz or quartzite (SiO₂)

Pink Granite / K-Feldspar

Alkali feldspar granite / Potassium feldspar (Microcline/Orthoclase)

Diamond (Cut Gemstone)

Carbon (C)

Jasper

Microcrystalline quartz (SiO2)

Weathered porphyritic volcanic rock (likely andesite or basalt)

Aphanitic to porphyritic andesite–basalt; composition commonly plagioclase, pyroxene, and minor iron oxides

Dyed howlite or turquoise imitation

Howlite: Ca₂B₅SiO₉(OH)₅; turquoise: CuAl₆(PO₄)₄(OH)₈·4H₂O

Tumbled yellow jasper or petrified wood fragment

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-oxide-bearing jasper

Tumbled green aventurine

Quartzite dominated by quartz (SiO₂), with green mica/fuchsite inclusions

Milky Quartz

Silicon Dioxide (SiO2)

Chert / Flint

Silicon Dioxide (SiO2)

Dyed Agate

SiO2 (Silicon Dioxide) - Chalcedony variety

Smoky Quartz with Feldspar

Quartz (SiO2) with Potassium Feldspar (KAlSi3O8)

Smoky Quartz Geode Slice

Silicon Dioxide (SiO2)

Mystic Topaz

Aluminum silicate fluoride hydroxide with titanium coating (Al2SiO4(F,OH)2)

Silicon Carbide (Carborundum)

Moissanite (SiC), though mostly synthetic

Chert (often called Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Granite

Felsic intrusive igneous rock

Dyed Crackle Quartz

Silicon Dioxide (SiO2) with artificial dye

Turquoise in Matrix

Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O

Chert (varieties: Flint or Jasper)

Microcrystalline Quartz (SiO2)

Tumbled blue sodalite (probable)

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Obsidian (likely blue-sheen or coated obsidian)

Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, noncrystalline)

Chert (variations include Flint)

Chert (SiO2)

Olivine (in Peridotite/Dunite form)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Quartz-bearing metamorphic rock, possibly epidote/quartzite

Quartz-rich rock with possible epidote and feldspar; exact identification requires testing

Vesicular basalt (weathered scoriaceous basalt)

Basalt; chiefly plagioclase, pyroxene, and commonly olivine (approximately 45–52% SiO₂)

Rounded reddish-brown pebble

Likely ferruginous sandstone or iron-rich quartzite; exact identification requires a fresh surface and tests

Likely quartz-rich pebble (possibly weathered quartzite)

Quartzite; predominantly SiO₂ (identification tentative from photograph)

Pink quartz (likely rose quartz)

Quartz, silicon dioxide (SiO₂)

Weathered iron-rich sandstone or laterite fragment

Ferruginous sandstone, chiefly quartz (SiO₂) cemented or stained by iron oxides/hydroxides

Granitic gneiss (weathered, rounded cobble)

Foliated granitoid; primarily quartz, feldspar, and mica (composition commonly approximates granite)

Banded chert (likely flint)

Microcrystalline quartz/chalcedony, SiO₂

Tumbled green stone, likely serpentine

Serpentinite; principally serpentine-group minerals, Mg₃Si₂O₅(OH)₄

Quartz-rich rock with chlorite/epidote vein

Milky quartz with green chlorite or epidote; exact identification requires testing

Quartz-rich translucent pebble, possibly iron-stained quartz or chalcedony

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)