Igneous, Sedimentary, Or Metamorphic (Mineral Based)

Quartz / Quartzite Fragment

Silicon Dioxide (SiO2)

Gold Mineral

Native Gold (Au)

Biotite Mica

Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)

Pyrite

Iron Pyrite (FeS2)

Pyrite (on Quartz/Host Rock)

Iron Sulfide (FeS₂)

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Orange Calcite

Calcium Carbonate (CaCO3)

Blue Sapphire (in a faceted jewelry setting)

Corundum (Al2O3) with trace Iron and Titanium

Gneiss

Gneiss (High-grade metamorphic rock)

Quartz

Silicon Dioxide (SiO₂)

Aquamarine

Beryl (Be3Al2Si6O18 with iron impurities)

Smoky Quartz Cluster

Smoky Quartz (Silicon Dioxide - SiO2)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Red Garnet

Pyrope or Almandine (Silicate group, X3Y2(SiO4)3)

Water and Silt (Sedimentary Environment)

Suspended Sediment / H2O (dihydrogen monoxide)

Black Tourmaline (Schorl)

Schorl (Sodium iron silicate hydroxide boron silicate); NaFe3Al6(BO3)3Si6O18(OH)4

Chalcedony (Grey/White Agate)

Silicon Dioxide (SiO₂)

Blue Sapphire

Corundum (Al2O3)

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.

Iolite (Cordierite)

Cordierite (Magnesium Aluminum Silicate), Mg2Al4Si5O18

Quartz / Quartz Cluster

Silicon Dioxide (SiO2)

Blue Kyanite

Kyanite (Al2SiO5)

Shungite

Non-crystalline carbon (allotrope of carbon)

Granitic Gneiss

Gneiss (High-grade Metamorphic Rock)

Rough Gemstone Grains (Mixed Sapphires and Quartz)

Corundum (Al2O3) and Quartz (SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Blue Sapphire

Corundum (Al2O3)

Kyanite (in Schist Matrix)

Kyanite (Al2SiO5)

Green Kyanite

Kyanite (Al2SiO5)

Greenstone (Greenschist facies)

Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals, Mg3Si2O5(OH)4)

Quartz / Quartzite

Silicon Dioxide (SiO2)

Kyanite

Kyanite (Al2SiO5)

Graphite

Graphite (C)

Labradorite

Labradorite ((Ca, Na)(Al, Si)4O8)

Lapis Lazuli

Na8(Al6Si6O24)S2 (Lazurite is the primary constituent mineral)

Blue Kyanite

Kyanite (Al2SiO5)

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Mixed Gemstone Collection

SiO2 (Quartz varieties) and Biogenic CaCO3 (Nacre)

Quartz

Quartz (SiO2 - Silicon Dioxide)

Native Gold (in the form of jewelry)

Gold (Au)

Anthracite Coal

Anthracite (Carbon based)