This Appears To Be A Man Made Metallic Object, Likely Jewelry, Not A Natural Rock, Mineral, Or Geological Specimen.

Gold Nugget

Native Gold (Au)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Mineral or Sedimentary Rock (with mineral inclusions)

Quartz (chalcedony variety) or Limestone with Quartz Veins

SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)

Carnelian

Carnelian (a variety of Chalcedony, SiO2)

Quartz pebble

Silicon Dioxide (SiO2)

Quartz (Milky or Druzy Quartz)

Silicon Dioxide (SiO2)

Placer Gold Nugget

Native Gold (Au)

Granite

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

igneous

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite

Chevron Amethyst

Silicon Dioxide (SiO2) with iron impurities

Sandstone Concretion

Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)

sedimentary

Agate

Agate (Silicon Dioxide, SiO2)

Sunstone

Aventurine Feldspar ((Ca,Na)(Al,Si)4O8)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Smoky Quartz (Vein Quartz)

Quartz (Silicon Dioxide, SiO2)

African Turquoise (Jasper)

Polychrome African Jasper (often marketed as 'African Turquoise' due to its color, but it is not true turquoise)

Rock

Lapis Lazuli

Lapis Lazuli (A metamorphic rock primarily composed of Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Amazonite (likely mixed with other feldspars/minerals)

Amazonite is a variety of Microcline, which is a tectosilicate mineral, formula KAISi3O8. The mixed beads could include other feldspars or quartz.

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron inclusions)

Smoky Quartz (Tumbled)

Silicon Dioxide (SiO2)

Jasper

Silicon dioxide (SiO2)

sedimentary

Lapis Lazuli (Simulated)

Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Basalt with Weathered Surface

Basalt

Igneous

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz Geode/Cluster

Quartz (SiO2)

Pyrite in Matrix (Commonly called Fool's Gold)

Iron Sulfide (FeS2)

Organic Gemstone/Biomineral

Mother of Pearl (Nacre)

Calcium Carbonate (primarily aragonite, with conchiolin)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

sedimentary

Quartz / Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Drusy/Crystalline variety)

Silicon Dioxide (SiO2)

Fluorite (often referred to as Rainbow Fluorite)

Fluorite (Calcium Fluoride, CaF2)

Sunstone and Green Aventurine

Sunstone: (Ca,Na)[(Al,Si)2Si2O8] (Plagioclase Feldspar Group); Green Aventurine: SiO2 (Quartz)

Hematite

Iron(III) oxide (Fe2O3)

Dendritic Agate or Spotted Quartzite

Silicon Dioxide (SiO2) with inclusions

Clear Quartz Cluster

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Azurite-Malachite (often called Azerite Malachite or Azurmalachite)

Azurite (Cu3(CO3)2(OH)2) and Malachite (Cu2CO3(OH)2)