Not A Natural Rock (Man Made Composite)

Pebble

Clast (specifically a granule or small pebble)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Blue Sapphire

Corundum (Al2O3)

Sandstone (with possibly iron oxides and other minerals)

Sandstone

Chert (Jasper variety) with Iron Oxide staining

Cryptocrystalline Quartz (SiO2) with Goethite/Limonite impurities

Polished yellow jasper or opaque chalcedony bead

Microcrystalline quartz (SiO₂), likely iron-oxide-stained jasper

Sandstone (likely a river or beach pebble)

Sandstone (a clastic sedimentary rock)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Layered shale and sandstone gorge

Shale and thin-bedded sandstone, likely Devonian or older sedimentary strata

Blue Sapphire

Corundum (Al2O3 with iron and titanium trace elements)

Weathered granite or granitic pegmatite cobble

Granite/granitic rock, composed mainly of quartz (SiO₂), feldspar, and minor biotite or other dark minerals; the reddish-brown areas may be iron-oxide staining or weathered accessory minerals

Agate Slices and Clear Quartz Points

Agate (SiO2 Chalcedony) and Clear Quartz (SiO2 Crystalline)

Lapis Lazuli

Lapis Lazuli (a rock type, not a single mineral, composed primarily of lazurite, calcite, and pyrite)

Black Tourmaline

Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)

Bowling Ball (Brunswick T-Zone Deep Space)

Polyester resin / Polyurethane polymer

Likely vertebra fossil or bone fragment

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

Quartzite Pebble

Quartzite (SiO2 with minor impurities)

Crushed Stone / Gravel (Multiple Rock Types)

Lithic fragments (undifferentiated)

Red Sandstone

Ferruginous Sandstone

Gold Nugget

Native Gold (Au)

Polished ocean jasper (orbicular jasper)

Microcrystalline quartz (SiO₂) with chalcedony, iron oxides, and assorted silicate inclusions

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Sandstone

Clastic sedimentary rock (quartz arenite)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Iron-Stained Quartz (Red/Hematoid Quartz)

Silicon Dioxide (SiO2) with Hematite/Goethite inclusions

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Milky Quartz with Iron Inclusions

Quartz (Silicon Dioxide, SiO2)

Granite pebble

Granite; chiefly quartz, potassium feldspar, plagioclase, and minor biotite/hornblende

Tumbled blue-green chrysocolla (likely chrysocolla with quartz)

Chrysocolla, hydrated copper aluminum silicate; commonly intergrown with quartz, Cu₂H₂Si₂O₅(OH)₄

Snowflake Obsidian

Volcanic Glass (SiO2 with Cristobalite inclusions)

Pink Fluorite

Fluorite (Calcium Fluoride) - CaF2

Clear Quartz

Silicon Dioxide (SiO2)

Turquoise

Hydrate phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Weathered sandstone or iron-stained sedimentary rock

Likely quartz-rich sandstone; exact identification is uncertain from the photograph

Black Onyx

Silicon dioxide (SiO2) with parallel banded structure

Ironstone / Limonite Concretion

Hydrated Iron Oxide Rock (FeO(OH)·nH2O with SiO2)

Emerald in Matrix

Beryl (Be3Al2(SiO3)6) embedded in schist or pegmatite host rock

Turquoise

Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O