Mineral Based Human Made Alloy

Aquamarine

Beryl (Be3Al2Si6O18)

Limonite (Iron Stone/Ocher)

Limonite (FeO(OH)·nH2O)

Pearl

Calcium Carbonate (CaCO3) + Conchiolin

Chert / Yellow Jasper

Microcrystalline Quartz (SiO2)

Chert with Limestone

Silicon Dioxide (SiO2) in Calcium Carbonate (CaCO3) Matrix

Chert (specifically Jasper or Flint variety)

Cryptocrystalline Quartz (SiO2)

Conglomerate

Sedimentary Conglomerate with Basaltic Clast

Siltstone with Fossil Cast

Sedimentary Rock (Siltstone / Fine-grained Sandstone)

Chert

Microcrystalline Quartz (SiO2)

Diorite

Diorite (Intermediate intrusive igneous rock)

Granite

Granite (Felsic Intrusive)

Chert (variations include Chalcedony and Flint)

Microcrystalline or Cryptocrystalline Quartz (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.

Amethyst (Purple), Sulfur (Yellow), and Blue Apatite

SiO2 (Quartz), S (Native Sulfur), Ca5(PO4)3(F,Cl,OH) (Apatite Group)

Bismuth

Bismuth (Bi)

Vanadinite

Vanadinite (Pb5(VO4)3Cl)

Pyrite (on Quartz/Host Rock)

Iron Sulfide (FeS₂)

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

Multiple (principally Silicon Dioxide SiO2 and Iron Disulfide FeS2)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Gabbro

Gabbro (Mg, Fe)2Si2O6 / (Ca, Na)(Al, Si)4O8

Sandstone (Pebble)

Sandstone (SiO2 dominated clastic sedimentary rock)

Amazonite

Amazonite (KAlSi3O8)

Ferrous Slag

Iron/Steel Slag (Complex Calcium-Alumino-Silicates)

Sandstone (likely Calcareous or Quartz-rich)

Arenite (SiO2 based typically)

Aura Quartz

Silicon Dioxide (SiO2) with metallic vapor coating

Sandstone (Ferruginous)

Arenite (SiO2 based with Fe2O3 banding)

Sandstone (lithic/arkosic)

Clastic sedimentary rock (primarily SiO2)

Ferro-silicate Slag

Industrial Vitrified Slag (High-silica amorphous glass)

Man-made Green Quartz (Lab-grown or Treated)

Silicon Dioxide (SiO2) with artificial coloration

Chert (Flint)

Chert (Microcrystalline or cryptocrystalline Quartz - SiO2)

Chert (specifically Zebra Chert/Flint)

Silicon Dioxide (SiO2)

Milky Quartz

Crystalline Silicon Dioxide (SiO2)

Green Tourmaline (Verdelite)

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

Blue Topaz (specifically London Blue shade)

Topaz - Al2SiO4(F,OH)2

Granite

Felsic intrusive igneous rock

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (SiO2 based with various mineral cements)

Tumbled Aventurine

SiO2 (Quartz with Fuchsite inclusions)

Opalite

Synthetic Glass, SiO2 base with metallic inclusions

Blue Kyanite

Kyanite (Al2SiO5)

Gold Nugget

Native Gold (Au)