Man Made Material

Sandstone (Quartzite Pebble)

Arenite (SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (SiO2 primarily)

Sandstone (Ferruginous)

Arenite (Fe2O3 enriched)

Sandstone

Arenite (SiO2 based)

Sandstone

Arenite (primarily Quartz, SiO2)

Sandstone (Red Sandstone)

Arenite (primarily Quartz with Hematite cement)

Quartzite Pebble

Quartzite (SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone (likely Quartz Sandstone)

Arenite (composed primarily of SiO2)

Massive Quartz

Silicon dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Sandstone (likely Arkosic or Lithic Sandstone)

Arenite (SiO2 based with mineral inclusions)

Sandstone (with vugs or solution cavities)

Arenite (primarily Quartz and Feldspar with CaCO3 or SiO2 cement)

Sandstone

Arenite

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

Granitic gneiss (weathered, rounded cobble)

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

Banded chert (likely flint)

Microcrystalline quartz/chalcedony, SiO₂

Likely quartz-rich pebble (possibly weathered quartzite)

Quartzite; predominantly SiO₂ (identification tentative from photograph)

Quartz-rich rock with chlorite/epidote vein

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

Pegmatitic granite

Granite, quartz–feldspar–mica assemblage

Weathered river stones, likely basaltic andesite and related volcanic rocks

Fine-grained mafic/intermediate volcanic rocks; commonly basalt (plagioclase + pyroxene ± olivine) or andesite (plagioclase + pyroxene ± amphibole)

Fossil shell fragment, likely brachiopod or bivalve

Indeterminate fossilized carbonate shell; possibly Spiriferida (brachiopod)

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

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

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)

Emerald

Beryl, Be₃Al₂(SiO₃)₆, colored green mainly by chromium and/or vanadium

Weathered quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Weathered quartz-rich rock fragment

Likely quartz-bearing feldspathic rock; exact identification requires testing

Iron-stained sandstone or weathered ironstone

Ferruginous sandstone; chiefly quartz (SiO₂) cemented or coated by iron oxides such as hematite (Fe₂O₃) and goethite (FeO(OH))

Serpentine

Serpentine Group (Mg3Si2O5(OH)4)

Rhodonite

Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3

Diamond (Set in Jewelry)

Carbon (C)

Limestone

Calcium Carbonate (CaCO3)

Marble

Recrystallized Calcite (CaCO3)

Olivine (Peridotite / Dunite Pebble)

(Mg,Fe)2SiO4 (Magnesium Iron Silicate)

Peridot in Matrix

Olivine ((Mg,Fe)2SiO4)

Rhodonite

Rhodonite ((Mn2+,Fe2+,Mg,Ca)SiO3)

Diamond

Carbon (C)

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