Not A Natural Rock

Red Sandstone

Arenite (with Iron Oxide)

Chert (Arrowhead/Artifact Fragment)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Granite

Phaneritic plutonic rock (primarily Quartz, Alkali Feldspar, and Plagioclase)

Granite

Granite (Mainly Quartz, Feldspar, and Mica)

Dyed Agate

Silicon Dioxide with artificial pigment (SiO2)

Diamond

Diamond (pure Carbon, C)

Quartzite

Quartzite (primarily SiO2)

Smoky Quartz on Matrix

Silicon Dioxide (SiO2) with trace impurities and aluminum inclusions

White Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Blue Lace Agate

Silicon Dioxide (SiO2)

Ferruginous Conglomerate

Ferruginous Conglomerate (Clastic Sedimentary Rock)

Chert Nodule (with Ironstone Cortex)

Microcrystalline Silica (SiO2)

Granite

Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert (Jasper variety) with Iron Oxide staining

Cryptocrystalline Quartz (SiO2) with Goethite/Limonite impurities

Clear Quartz

Silicon Dioxide (SiO2)

Granite (Weathered River Rock)

Plutonic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Halite (Himalayan Pink Salt)

Halite - NaCl (Sodium Chloride)

Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Granite

Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Agate and Amethyst (Quartz variants)

Silicon Dioxide (SiO2) - Microcrystalline Quartz and Crystalline Quartz

Turquoise

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

Cubic Zirconia (in Jewelry)

Zirconium Dioxide (ZrO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Coral Rock (Coquina)

Biogenic Limestone (Calcium Carbonate - CaCO3)

Sandstone (with Liesegang rings or joints)

Clastic Sedimentary Rock (primarily Quartz with Iron Oxide cement)

Amber (Simulated/Faturan Style)

Resin mix (Likely Phenolic/Celluloid if synthetic, Succinite if natural)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Gold Nugget

Native Gold (Au)

Schist (Kyanite Schist)

Kyanite-Mica Schist (primarily Al2SiO5, KAl2(AlSi3O10)(OH)2, and SiO2)

Quartz (Engineered Quartz Surface)

Silicon Dioxide (SiO2) based composite

Diamond

Carbon (C)

Diamond (or Cubic Zirconia)

Carbon (C) / Cubic Zirconium Dioxide (ZrO2)

Engineer Quartz/Quartzite

SiO2 (Silicon Dioxide with binders)

Prasiolite (Green Quartz)

Silicon Dioxide (SiO2) with iron impurities

Clear Quartz

Silicon Dioxide (SiO2)

Quartzite Pebble

Quartzite (SiO2 with minor impurities)

Shale

Fissile Clay-dominant Mudrock (SiO2, Al2O3, K2O, Na2O, CaO, MgO)

Goldstone (with Tiger's Eye and Quartz)

Aventurine glass (Synthetic SiO2 with Cu inclusions)

Blue Sapphire

Corundum (Al2O3)