Metamorphic Or Sedimentary

Unakite

Epidotized Granite

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Quartzite with Chlorite/Epidote

Metamorphosed Quartzite (SiO2)

Fuchsite

K(Al,Cr)2(AlSi3O10)(OH)2 (Chromium-rich Muscovite)

Magnetite

Magnetite (Fe3O4)

Mica in Quartz Host

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

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

Rhodonite

Rhodonite (Manganese silicate), (Mn,Fe,Mg,Ca)SiO3

Muscovite Mica

Muscovite: KAl2(AlSi3O10)(OH)2

Zoisite with Ruby

Anyolite (Ca2Al3(SiO4)3(OH) with Al2O3:Cr)

Nephrite Jade

Ca2(Mg, Fe)5Si8O22(OH)2

Schist

Schist (various mineral compositions)

Blue Sapphire

Corundum (Al2O3)

Unakite (Epidotized Granite)

Unakite; primarily composed of Epidote (Ca2(Al,Fe)3(SiO4)3(OH)), Orthoclase (KAlSi3O8), and Quartz (SiO2)

Schist

Mica Schist (predominantly Muscovite or Biotite)

Anthracite Coal

Anthracite (Carbon-rich metamorphic coal)

Quartzite (River-worn Shiner)

Quartzite (Formula: 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.

Greenschist

Chlorite schist

Cream Marble (Speckled)

Metamorphosed Limestone (mainly CaCO3)

Biotite (Black Mica)

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

Greenschist / Chloritaform Schist

Chlorite Schist (Group of Silicate Minerals)

Quartzite

Quartzite (primarily SiO2)

Quartzite pebble

Quartzite (SiO2)

Epidote in Matrix (Unakite-related)

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

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

River Quartzite (or Quartz Cobble)

Quartzite (primarily Silicon Dioxide - SiO2)

Fuchsite Gneiss (Green Quartzite)

Chromium-rich Muscovite (KAl2(AlSi3O10)(OH)2 with Cr replacements)

Marble

Metamorphic rock composed of Recrystallized Carbonate Minerals (chiefly CaCO3)

Milky Quartz

Silicon Dioxide (SiO2)

Pink Quartz (Rose Quartz variant)

Silicon Dioxide (SiO2)

Quartzite Cobble

Quartzite (primarily SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartzite

Quartzite (SiO2)

Gossan (Iron Hat)

Limonitic Gossan (Fe-oxide/hydroxide complex)

Quartzite

Quartzite (SiO2)

Quartzite

Quartzite (SiO2)

Unakite

Epidotized Granite

Schist (specifically Mica Schist)

Mica Schist

Garnet-Bearing Schist

Almandine Garnet Micaceous Schist