Igneous, Sedimentary, And Metamorphic

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Chalcedony (Agate/Chert)

Silicon Dioxide (SiO2)

Botryoidal Chalcedony

Silicon Dioxide (SiO2)

Muscovite Schist

Muscovite Mica Schist (KAl2(AlSi3O10)(OH)2)

Quartz on Schist

Silicon Dioxide (SiO2) on Foliated Metamorphic Rock

Garnet-bearing Schist

Almandine Garnet (Fe3Al2(SiO4)3) in Mica Schist

Quartz with Mica (likely Muscovite)

Silicon Dioxide (SiO2) with Potassium Aluminum Silicate Hydroxide Fluoride

Mica Schist

Mica Schist (primarily Muscovite and/or Biotite composition)

Banded Slate (Lithified Mudstone)

Low-grade Metamorphosed Mudstone / Slate

Mica Schist

Mica Schist

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite

Diamond Drill Core (Greenschist and Quartzite)

Chlorite Schist / Meta-quartzite (Metamorphic Rock Core Sample)

Green Aventurine

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

Garnet (specifically Almandine)

Almandine (Fe3Al2(SiO4)3)

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)

Chrysocolla

Hydrated copper phyllosilicate, Cu2-xAlx(H2-xSi2O5)(OH)4·n(H2O)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Pyrite on Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Citrine (Yellow Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine/Lemon Quartz)

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Blue Quartz with Dumortierite/Magnesio-riebeckite inclusions

Quartz (SiO2) containing Dumortierite (Al7(BO3)(SiO4)3O3)

Citrine Quartz

Silicon Dioxide (SiO2)

Quartz Pebble (Sea Glass-like Quartz)

Quartz (Silicon Dioxide - SiO2)

Dalmatian Stone (commonly called Dalmatian Jasper)

Peralkaline Rock (mixed Feldspar, Quartz, and Arfvedsonite)

Black Star Diopside

Diopside (CaMgSi2O6) with asterism

Jasper

Jasper (Silicon Dioxide, SiO2)

Pink Quartzite

Quartzite (SiO2 with iron oxide inclusions)

Quartzite

Quartzite (SiO2)

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Orange Quartzite (Tumbled)

Quartzite (SiO2)

Granite Gneiss

Gneiss (High-grade regional metamorphic rock)

Blue Quartz (Aventurine)

Silicon Dioxide (SiO2) with Crocidolite or Magnesio-riebeckite inclusions

Marble

Recrystallized Calcite (CaCO3)

Anthracite Coal

Anthracite (Carbon based fossil fuel)

Milky Quartz

Silicon Dioxide (SiO2)

Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Orange Calcite

Calcite (Calcium Carbonate - CaCO3)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Blue Calcite

Calcium Carbonate (CaCO3)