Organic Gemstone (Often Associated With Sedimentary Sequences)

Chert (often called Jasper in this color variety)

Microcrystalline Quartz (SiO2)

Moonstone

Adularia or Orthoclase (KAlSi3O8) or Albite (NaAlSi3O8), specifically with lamellar exsolution of albite and orthoclase.

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2)

Chert (Chert / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Granitic Pegmatite

Granite Pegmatite (principally KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)

Clear Quartz

Silicon Dioxide (SiO2)

Ironstone Concretion (Limonite/Hematite Nodules)

Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)

Chert (often called Flint or Jasper locally)

Chert (Microcrystalline Quartz, Formula: SiO2)

Chert (often called Flint)

Chert (Microcrystalline Quartz, SiO2)

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Chert (variations include Flint or Jasper)

Silicon Dioxide (SiO2)

Banded Chert with Quartz Veining

Microcrystalline Quartz (SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Synthetic Costume Accessory (Non-Geological)

Polyester and Acrylic Fiber (Anthropogenic polymer)

Greenstone

Chlorite schist or metabasalt depending on specific composition

Lepidolite on Matrix

K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2

Sandstone with Fossil Leaf Impression

Sedimentary rock (Sandstone/Siltstone matrix) with Carbonaceous film fossil

Yellow Agate

Silicon Dioxide (SiO2)

Native Copper

Native Copper (Cu)

Anthracite Coal

Anthracite (Carbon-rich metamorphic coal)

Unakite

Epidotized Granite

Pearl

Organic gemstone (Calcium carbonate / CaCO3 + Conchiolin)

Quartz (Druzy / Goldstone Gemstone Cabochon)

Silicon Dioxide (SiO2)

Jade

Jadeite or Nephrite (both are commonly referred to as 'jade'). Jadeite: NaAlSi2O6; Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2.

Limestone

Calcareous sedimentary rock (CaCO3)

Green Fluorite

Calcium Fluoride (CaF2)

Lepidolite Pebble

K(Li,Al)3(Al,Si,3O10)(F,OH)2

Lepidolite

K(Li,Al)3(Al,Si,IV)4O10(F,OH)2

Bornite

Bornite (Cu5FeS4)

Unakite (or Epidote-rich Granite)

Unakite (composed of Epidote {Ca2(Al, Fe)3(SiO4)3(OH)}, Pink Orthoclase Feldspar {KAlSi3O8}, and Quartz {SiO2})

Peacock Ore

Bornite (Cu5FeS4) or Chalcopyrite treated with acid

Molybdenite in Quartz

Molybdenite (MoS2) with Quartz (SiO2)

Native Gold Nugget

Native Gold (Au)

Diorite

Diorite

Rose Quartz

Silicon dioxide (SiO2)

Bornite

Bornite (Cu5FeS4)

Arsenopyrite

Arsenopyrite (FeAsS)

Arsenopyrite in Sulphide Ore

Arsenopyrite (FeAsS)

Arsenopyrite

Arsenopyrite (FeAsS)

Yellow Jasper

Chalcedony (Silicon Dioxide, SiO2)