Igneous, Sedimentary, Metamorphic, Mineral

Quartz (Milky Quartz)

Quartz (Silicon Dioxide, SiO2)

Schorl (Black Tourmaline)

Sodium Iron Aluminum Borosilicate Hydroxide; NaFe2+3Al6Si6O18(BO3)3(OH)3OH

Yellow Quartz / Citrine Quartz

Silicon Dioxide (SiO2)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Quartz (River Pebble)

Quartz (SiO₂ - Silicon Dioxide)

Tumbled Rose Quartz

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Specular Hematite with Quartz and Limonite

Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)

Orange Calcite

Calcium Carbonate (CaCO3)

Tumbled Agate

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Vein in Pelite (Metamorphic Rock)

Hydrothermal Quartz Veining in Metasedimentary Rock (SiO2)

Dalmatian Jasper

Peralkaline rhyolite with arfvedsonite inclusions

Garnet

Garnet Group (Silicate Minerals), formula varies e.g., Almandine Fe3Al2(SiO4)3

Garnet

Garnet Group (e.g., Almandine Fe3Al2(SiO4)3)

Rutilated Quartz

Quartz (SiO2) with Rutile (TiO2) inclusions

Epidote in Matrix (Unakite-like Rock Fragment)

Epidote (Ca2(Al,Fe)3(SiO4)3(OH)) / Altered Metamorphic Pebble

Biotite (Black Mica)

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

Mica Schist

Schist (biotite/muscovite schist)

Granitic Gneiss

Gneiss (Metamorphic rock of granitic composition)

Banded Slate

Slate (Metamorphosed Siltstone/Mudstone)

Mica in Quartz Host

Muscovite (KAl2(AlSi3O10)(OH)2) in Quartz (SiO2)

Quartz (Chalcedony/Agate)

Silicon Dioxide (SiO2)

Gneiss

Feldspar–quartz–mica gneiss, locally amphibole-bearing

Gold Nugget / Placer Gold

Native Gold (Au)

Amazonite

Microcline (variety Amazonite), K(AlSi3O8)

Strawberry Quartz (or Hematoid Quartz)

Silicon Dioxide (SiO2) with inclusions of Hematite or Goethite

Purple Dyed Dalmatian Stone

Dyed Peralkaline Trachyte

Quartz with Mica and Feldspar

Granitic Pegmatite Fragment (SiO2 + KAlSi3O8 + KAl2(AlSi3O10)(OH)2)

Pyrite in Matrix (often with Chalcopyrite)

Iron Sulfide (FeS2) / Copper Iron Sulfide (CuFeS2)

Unidentified Dark Mineral or Rock

Indeterminate (Likely Silicon Dioxide or Carbon-based)

Green Schist (Greenschist)

Greenschist facies metamorphic rock

Greenstone (Epidosite)

Epidosite (Metamorphosed Basalt/Diabase)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Epidote

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

Quartz–mica metamorphic rock, likely schist

Quartz–muscovite/biotite schist; predominantly SiO₂ quartz with phyllosilicate micas

Pyrite

Iron Sulfide (FeS2)

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Brown Marble

Metamorphic Limestone (CaCO3)

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.

Yellow Calcite

Calcium Carbonate (CaCO3)

Epidosite

Epidosite (consisting primarily of Epidote Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH) and Quartz SiO2)