Mineral And Organic Gemstone

Pyrite

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Quartz Pebble

Silicon Dioxide (SiO2)

Given the appearance, it's likely a fragment of an igneous or metamorphic rock composed of multiple minerals. Without specific diagnostic features, it's difficult to give a common name other than 'crystalline rock fragment'. If pressed to guess based on the granular, somewhat light and dark speckled appearance, it could be a fragment of granite or a related intrusive igneous rock.

As a rock fragment, it does not have a single scientific mineral name; rather, it's a piece of a rock which is a combination of minerals. If it were granite, its main mineral composition would be quartz (SiO2), feldspar (e.g., KAlSi3O8 - orthoclase, (Na,Ca)(Al,Si)4O8 - plagioclase), and mica (e.g., KAl2(AlSi3O10)(OH)2 - muscovite or K(Mg,Fe)3AlSi3O10(OH)2 - biotite), among others.

Pink Tourmaline (Rubellite) in Lepidolite

Elbaite (Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)4) in Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals like Antigorite, Lizardite, and Chrysotile)

Puddingstone (Jasper-Conglomerate)

Conglomerate (Silicon Dioxide, SiO2 with impurities)

Lepidolite

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

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within a metamorphic matrix

Diamond (in a jewelry setting)

Cubic Carbon (C)

Banded Gneiss

Gneiss (High-grade Metamorphic Rock)

Smoky Quartz

SiO2 (Silicon Dioxide)

Granite

Phaneritic Plutonic Rock (High Silica content)

Glauconitic Sandstone

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

Chert (and Jasper/Chalcedony variety)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Cryptocrystalline Quartz (SiO2)

Glauconite (Greensand Articulated Sandstone)

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

Fossil Shark Tooth

Selachimorpha (Chondrichthyes dental fossil)

Glauconite

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

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Pyrite

Iron Disulfide (FeS2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Pyrite

Iron Disulfide (FeS2)

River Cobble (Sandstone)

Arenite (primarily SiO2)

Chert (Jasper/Agate Peat)

Microcrystalline Quartz (SiO2)

Chert (often called Flint or Chalcedony Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Gray River Pebble (likely Limestone or Siltstone)

Sedimentary Rock (Calcium Carbonate or Siliciclastic)

Chert (with Epidote/Quartz veining)

Cryptocrystalline silica (SiO2) with Epidote/Quartz inclusions

Sandstone (likely Fossiliferous Sandstone)

Clastic sedimentary rock (primarily SiO2)

Fossilized Shark Tooth (Otodus)

Otodus obliquus

Chert (variations include Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pearl

Aragonite and Conchiolin (CaCO3 + organic protein)

Pink Granite Pebble

Granite (Phaneritic igneous rock)

Quartz in Basalt (Xenocryst)

Silicon Dioxide (SiO2) in Mafic Igneous Volcanic Rock

Fossilized Shark Tooth

Carcharhinus sp. (likely Bull or Requiem shark family)

Pearl

Calcium Carbonate (Aragonite) - CaCO3

Petrified Wood

Silicified Wood (primarily SiO2)

Quartz (Milky/Rose variety)

Silicon Dioxide (SiO2)

Pyrite

Pyrite (Iron Disulfide), FeS2

Cubic Zirconia (Faceted)

Zirconium dioxide (ZrO2)

Fossilized Bone Fragment

Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)