Organic Mineraloid And Mineral

Dendritic Agate

Silicon Dioxide with inclusions (SiO2 + Mn/Fe)

Chert (Jasper/Flint Pebble)

Microcrystalline quartz (SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Diamond in Kimberlite

Diamond (C in Kimberlite Matrix)

Quartz Geode

Silicon Dioxide (SiO2)

Sandstone Geode (Unbroken)

Siliciclastic sedimentary rock (primarily Quartz)

Quartz (Smoky/Milky variety)

Silicon Dioxide (SiO2)

Concretionary Sandstone

Clastic Sedimentary Rock (Sandstone with secondary mineral cementation)

Chert (often called Flint or Jasper if reddish)

Microcrystalline Quartz (SiO2)

Glauconitic Sanstone (Glauconite)

Glauconite ((K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Ocean Jasper (Orbicular Jasper)

Spherulitic Chalcedony (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Quartz with Arsenopyrite

Silicon Dioxide (SiO2) with Iron Arsenic Sulfide (FeAsS)

Copper Nugget

Native Copper (Cu)

Chert (Jasper/Chalcedony)

Microcrystalline Quartz (SiO2)

Dalmatian Stone

Dalmatian Jasper (Aplitic Rock)

Garden Quartz (Phantom Quartz)

Silicon Dioxide (SiO2) with inclusions (Chlorite, Feldspar, Goethite, Hematite)

Precious Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Mother of Pearl (Nacre)

Aragonite (layered with organic polymers), CaCO3

Pearl

Organic gemstone (Calcium carbonate - CaCO3)

Purple Agate (Dyed Chalcedony)

SiO2 (Silicon Dioxide) with organic dyes

Chert Pebble (Jasper/Quartz variety)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Moss Agate

Silicon dioxide (SiO2) with mineral inclusions

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Red Jasper

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

Sandstone Chert Concretion

Silica-cemented Concretion (primarily SiO2)

Fossilized Echinoid (Sea Urchin)

Echinoidea (Class)

Sandstone

Arenite (SiO2 based typically)

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Petoskey Stone (Petrified Favosites)

Favosites (extinct colonial coral), CaCO3 with Silica replacement

Sandstone

Arenite (SiO2 based)

Spondylus Oyster Calcification / Fossilized Oyster

Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)

Chert (Flint variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (and/or River Pebble)

Microcrystalline quartz (SiO2)

Dendritic Limestone

Calcite with Manganese Oxide (Manganese Dendrites)

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Tahitian Pearl

Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3

Jasper (Red-Brown)

Silicon Dioxide (SiO2) with Iron Oxide impurities