Metamorphic Or Mineral

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(F,OH)2)

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–mica gneiss

Likely schist, possibly serpentinite

Mica schist; potential chlorite–serpentine-rich metamorphic rock

Hematite

Iron Oxide (Fe2O3)

Rhodonite

Rhodonite (Manganese Iron Magnesium Calcium Silicate - (Mn,Fe,Mg,Ca)SiO3)

Quartz with Iron Oxide Inclusions

Silicon dioxide with limonite/hematite (SiO2)

K-Feldspar (Potassium Feldspar)

Potassium Feldspar (KAlSi3O8)

Citrine

SiO2 (Silicon Dioxide)

Pyrite in Matrix

Iron Sulfide (FeS2) embedded in host rock

Blue Apatite

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

Quartz

SiO2 (Silicon Dioxide)

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Quartz Crystal Cluster / Quartzite

Silicon Dioxide (SiO2)

Quartz with Matrix

Silicon Dioxide (SiO2)

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite

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.

Small rough mineral/rock fragment

Indeterminate; possibly quartz-bearing rock or weathered feldspar

Quartz Heart or Arrowhead Shape

Silicon Dioxide (SiO2)

Mica schist

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

Slate

Slate (Metamorphic Rock)

Rhodonite (in matrix)

Rhodonite (Mn,Fe,Mg,Ca)SiO3

Rhodonite

Manganese Silicate (Mn,Fe,Mg,Ca)SiO3

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Natural Gemstone Cabochons (Ruby, Moonstone, Emerald, Citrine)

Ruby (Al2O3:Cr), Moonstone (KAlSi3O8), Emerald (Be3Al2(SiO3)6:Cr), Citrine (SiO2)

Rhodonite

(Mn,Fe,Mg,Ca)SiO3

Quartz

Silicon dioxide (SiO2)

Garnet Schist

Almandine-bearing Mica Schist

Serpentine-bearing metamorphic rock (likely chromite/vesuvianite-bearing serpentinite)

Serpentinite, chiefly serpentine-group minerals [(Mg,Fe)₃Si₂O₅(OH)₄], with dark accessory minerals

Biotite Schist

Schist (Biotite-dominated)

Quartz Crystal in Matrix

Silicon Dioxide (SiO2)

Feldspar

KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8 (Feldspar group)

Clear Quartz

Silicon dioxide (SiO2)

Quartzite with Dendritic Manganese Oxide Inclusions

Metamorphic Quartzite (SiO2 with Mn-oxides)

Quartzite

Metamorphic Quartzite (SiO2)

Chrysocolla on Matrix

Hydrated copper silicates ((Cu,Al)2H2Si2O5(OH)4·nH2O)

Gneiss

High-grade Metamorphic Gneiss

Ruby in Kyanite

Corundum in Disthene (Al2SiO5 + Al2O3)

Blue Zircon

Zircon (Zirconium Silicate), ZrSiO4

Quartz pebble with iron staining

Silicon dioxide (SiO2) with iron oxide inclusions

Orange Calcite

Calcium Carbonate (CaCO3)

Rose Quartz

Silicon Dioxide (SiO2)

Pink Quartz

Silicon Dioxide (SiO2)