Mineral (Metamorphic Pseudomorph)

Green Quartz (Prasiolite/Adventurine)

Silicon Dioxide with inclusions (SiO2)

Bornite

Bornite (Cu5FeS4)

Bornite

Bornite (Cu5FeS4)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Schist

Mica Schist

Banded Gneiss

Gneiss (Metamorphic Rock)

Schist

Crystalline Metamorphic Rock (Schistose)

Garnet (Almandine/Pyrope series)

Silicate mineral (Almandine: Fe3Al2Si3O12; Pyrope: Mg3Al2Si3O12)

Marble

Metamorphic rock composed of Recrystallized Carbonate Minerals (chiefly CaCO3)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Blue Kyanite

Kyanite (Al2SiO5)

Brown Marble

Metamorphic Limestone (CaCO3)

Pyrite

Iron Disulfide (FeS2)

Fluorite (left), Sodalite (middle), Dumortierite/Tumbled Quartzite (right)

Calcium Fluoride (CaF2), Sodium Aluminum Silicate Chloride (Na8(Al6Si6O24)Cl2), Aluminum Borosilicate (Al7(BO3)(SiO4)3O3)

Gneiss

Gneiss

Banded gneiss (likely amphibolite-bearing gneiss)

Gneiss; quartz–feldspar–mica/amphibole aggregate

Quartz (Smoky/Brown variety)

Silicon dioxide (SiO2)

Biotite Schist

Biotite Schist

Tumbled rhodonite

Rhodonite, manganese inosilicate (MnSiO₃), commonly mixed with quartz and manganese oxides

Garnet-bearing gneiss

Biotite–feldspar gneiss with almandine garnet; quartz likely present

Strawberry Quartz (Quartz with Hematite inclusions)

Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3)

Chalcopyrite (Peacock Ore)

Copper Iron Sulfide (CuFeS2)

Banded gneiss pebble

Gneiss, typically quartz–feldspar–mica; exact mineral composition requires testing

Quartz Vein in Pelite (Metamorphic Rock)

Hydrothermal Quartz Veining in Metasedimentary Rock (SiO2)

Gneiss

Gneiss (Metamorphic Rock)

Epidote

Epidote - {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)

Orange Calcite (likely polished specimen)

Calcite

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Bornite

Bornite (Cu5FeS4)

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–mica gneiss

Likely schist, possibly serpentinite

Mica schist; potential chlorite–serpentine-rich metamorphic rock

Apatite

Calcium phosphate fluoride/chloride, Ca5(PO4)3(F,Cl,OH)

Sapphire

Corundum (Al2O3)

Blue Apatite

Fluorapatite / Apatite (Ca5(PO4)3(F,Cl,OH))

Graphite

Graphite (C)

Green Quartz (Aventurine)

Silicon Dioxide with Fuchsite inclusions (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)

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.

Quartz pebble

Silicon dioxide (SiO2)

Mica schist

Schist dominated by muscovite/biotite mica, commonly with quartz and feldspar