Mineral Based Human Made Alloy

Conglomerate

Sedimentary Conglomerate with Basaltic Clast

Granite Pebble

Granite (Phaneritic intrusive igneous rock)

Veined Limestone

Sedimentary Calcite-Veined Rock (CaCO3)

Slag

Glassy silicate byproduct (anthropogenic material)

Geode half

Geode (often quartz/chalcedony based)

Shungite

Shungite (carbon-rich Precambrian rock)

Mineral Sand (Heavy Mineral Sand Concentrate)

Placer deposit concentrate containing minerals such as ilmenite, rutile, zircon, and magnetite

Bivalve Fossil (Clam Stone)

Phylum Mollusca, Class Bivalvia

Rough Gemstone Grains (Mixed Sapphires and Quartz)

Corundum (Al2O3) and Quartz (SiO2)

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate)

Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Milky Quartz

Silicon Dioxide (SiO2)

Aquamarine

Beryl (Be3Al2Si6O18)

Concretion

Calcareous or ferruginous concretion

Gold Nugget

Native Gold (Au)

Gold

Gold (Native Element); Au

Chrysocolla in Matrix

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

Chert (Commonly known as Flint)

Silicon Dioxide (SiO2)

Coquina

Coquina (Bioclastic Limestone)

Chert Arrowhead (Projectile Point)

Microcrystalline Quartz (Chert/Flint)

Tektite (Indochinite)

Natural glass (High-silica impact glass)

Polished tree agate (likely)

Chalcedony (microcrystalline SiO₂) with green dendritic/inclusion minerals

Jasper Agate (Carnelian Jasper)

Silicon Dioxide (SiO2) with iron oxide inclusions

Blue Dyed Agate

Silicon Dioxide (SiO2) with artificial pigment

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Black tourmaline (schorl)

Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Pyrite (on Quartz/Host Rock)

Iron Sulfide (FeS₂)

Mixed Tumbled Gemstones (Agate, Aventurine, Pyrite, etc.)

Multiple (principally Silicon Dioxide SiO2 and Iron Disulfide FeS2)

Pearl

Calcium Carbonate (CaCO3) + Conchiolin

Coquina

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sandstone (Red Sandstone)

Arenite (SiO2 based with Fe2O3 staining)

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.

Limestone

Calcium Carbonate (CaCO3)

Granodiorite

Granodiorite

Sandstone (River Rock)

Arenite (SiO2 based sedimentary rock)

Amazonite

Amazonite (KAlSi3O8)

Heat-Treated Amethyst (Citrine Geode)

Silicon Dioxide (SiO2) with iron impurities

Green Tourmaline (Verdelite)

Complex sodium iron aluminum borosilicate (Na(Mg,Fe,Li,Al,Mn)3Al6(BO3)3Si6O18(OH)4)

Sandstone

Sandstone (Silicon dioxide, SiO2 based)

Coquina

Biogenic Limestone (mostly Calcium Carbonate, CaCO3)

Chrysocolla in Matrix

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

Concrete aggregate surface

Human-made cementitious composite; primarily calcium-silicate-hydrate cement with mixed silicate aggregate