Mineral, Organic Gemstone

Chert (White Chert / Flint)

Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)

Sunstone

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

Rutilated Prehnite

Prehnite - Ca2Al(AlSi3O10)(OH)2 with Epidote/Tourmaline inclusions

Beryl (likely Emerald or Aquamarine in matrix)

Beryllium aluminum silicate (Be3Al2Si6O18)

Carnelian

Carnelian (subset of Chalcedony); SiO2 with Iron Oxide impurities

Chert (Red Jasper variant)

Microcrystalline Quartz (SiO2)

Septarian Nodule

Septarian Concretion (CaCO3 with Siderite/Calcite/Aragonite)

Jasper

Jasper (Silicon Dioxide, SiO2)

Banded Chert

Microcrystalline Quartz (SiO2)

Chert (specifically Flint or Common Chert)

Chert (Cryptocrystalline Silica, SiO2)

Chert / River Jasper

Microcrystalline Quartz (SiO2)

Ironstone Concretion (Limonite/Goethite)

Iron oxide concretion (contains FeO(OH)·nH2O)

Petrified Wood

Silicified Wood (primarily SiO2)

Coral Fossil (Petrified Coral)

Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)

Travertine (often colloquially called Tufa)

Chemical Sedimentary Calcium Carbonate (CaCO3)

Petrified Wood

Silicified Wood (primarily Quartz / Chalcedony: SiO2)

Petrified Wood

Silicified Wood (SiO2)

Rhodochrosite

Manganese Carbonate (MnCO3)

Brachiopod Fossil in Limestone

Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)

Chert (often called Flint)

Chert (Microcrystalline Quartz, SiO2)

Feldspar (Orthoclase)

Orthoclase Feldspar (KAlSi3O8)

Sunstone (Heliolite)

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

Emerald in Host Rock

Beryl (Be3Al2Si6O18) containing Chromium and/or Vanadium

Septarian Nodule (Dragon Stone)

Septarian Concretion (CaCO3 with Siderite and Calcite)

Jasper

Agate/Jasper (Microcrystalline Quartz, SiO2)

Septarian Nodule (Dragon Stone)

Septarian Geode (CaCO3 + Mg + Fe)

Chert (Nodule)

Silicon Dioxide (SiO2)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and organic impurities

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Petrified Wood

Silicified Wood (SiO2)

Rhodochrosite

Manganese carbonate (MnCO3)

Clear Quartz / Rock Crystal

Silicon Dioxide (SiO2)

Baroque Pearl (and potentially a small Sapphire/Blue Topaz)

Pearl: Calcium Carbonate (aragonite or calcite) with conchiolin. Sapphire: Aluminum Oxide (Al2O3). Blue Topaz: Al2SiO4(F,OH)2.

Gemstone Sand (Mineral Assortment)

Mixed Mineral Concentrates (Commonly including Quartz SiO2, Garnet X3Y2(SiO4)3, and Tourmaline (Na,Ca)(Li,Mg,Al)3(Al,Fe,Mn)6(BO3)3(Si6O18)(OH,F)4)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Emerald in Matrix

Emerald (Beryllium Aluminum Silicate), Be3Al2(SiO3)6

Sunstone (Oregon Sunstone)

Labradorite (Feldspar variety) - (Ca, Na)(Al, Si)4O8

Lapis Lazuli

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

Emerald in Matrix

Beryl (Be3Al2Si6O18) with trace amounts of Chromium/Vanadium

Chert (often called Flint when in chalk or limestone)

Silicon Dioxide (SiO₂)

Petrified Wood

Silicified Wood (SiO2)

Black Marble with Quartz Veining

Metamorphosed Limestone (Recrystallized CaCO3)