Mineral Based Alloy (Anthropogenic)

Sparkling Druzy Quartz on Matrix

Silicon Dioxide (SiO2) with iron oxide inclusions

Sandstone

Arenite (composed primarily of SiO2)

Amber in Matrix

Succinite (Carbon-based organic polymer)

Native Copper

Native Copper (Cu)

Sandstone (Quartz Sandstone)

Arenite (primarily SiO2)

Sandstone

Arenite (primarily SiO2 with trace Fe2O3)

Sandstone (with banding/weathering)

Clastic Sedimentary Rock (primarily SiO2)

Quartz / Quartz Cluster

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Sandstone

Arenite (primarily SiO2)

Iron Slag

Iron/Steel Slag (Ferrosilicate Glass)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Sandstone

Arenite (SiO2 based with various mineral cements)

Limonite (Iron Stone)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

Kyanite (in Schist Matrix)

Kyanite (Al2SiO5)

Kyanite

Kyanite (Al2SiO5)

Sandstone

Arenite (SiO2 based clastic rock)

Gold Nugget

Native Gold (Au)

Synthetic Costume Accessory (Non-Geological)

Polyester and Acrylic Fiber (Anthropogenic polymer)

Cubic Zirconia (Man-made)

Cubic Zirconia (ZrO2) with Enamel and Metal Alloy

Beryllonite

Beryllonite (NaBePO4)

Moss Agate

Silicon Dioxide (SiO2) with inclusions

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.

Blue Sapphire

Corundum (Al2O3)

White Topaz

Aluminum Silicate Fluoride Hydroxide; Al2SiO4(F,OH)2

Sandstone (Quartzose Sandstone)

Arenite (primarily SiO2)

Sandstone

Arenite (SiO2 based with various mineral cements)

Sandstone

Arenite (SiO2-rich)

Banded Calcite (Mexican Onyx)

Calcite (Calcium Carbonate, CaCO3)

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Tiffany Stone

Bertrandite (Be4Si2O7(OH)2) mixed with Fluorite (CaF2), Opal, and Chalcedony

Zebra Jasper

Tumbled Opaque Chalcedony (SiO2)

Celestite (Celestine)

Strontium Sulfate (SrSO4)

Celestite (Celestine)

Strontium Sulfate (SrSO4)

Sandstone (likely Ferruginous)

Sandstone (SiO2 with iron oxides)

Blue Chalcedony

Chalcedony (SiO2)

Greenstone (Greenschist facies)

Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)

Chert (Arrowhead variety)

Chert (SiO2)

Sandstone (Banded Sandstone)

Clastic Sedimentary Rock (primarily SiO2 with iron oxide impurities)

Moss Agate

Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)

Amethyst

Amethyst (Silicon Dioxide with iron impurities), SiO2