Synthetic Polymer (Synthetic Material)

Labradorite (a variety of Anorthosite or Plagioclase)

Labradorite (member of Plagioclase Feldspar series), (Ca,Na)(Al,Si)4O8

Kyanite (Blue Kyanite)

Kyanite (Al2SiO5)

Basalt with Scoria/Vesicular Texture

Extrusive Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Sandstone (specifically Arkose or Quartz Arenite)

Arenite (primarily SiO2 with possible Feldspar)

Quartz

Quartz (SiO2 - Silicon Dioxide)

Rose Quartz

Silicon Dioxide with traces of Titanium, Iron, or Manganese (SiO2)

Rose Quartz

Quartz (Silicon Dioxide - SiO2)

Turquoise

Turquoise (Hydrated phosphate of copper and aluminium) - CuAl6(PO4)4(OH)8·4H2O

Banded Chert (Flint)

Cryptocrystalline Quartz (SiO2)

Sandstone

Sandstone (lithified quartz arenite, arkose, graywacke, etc. depending on composition)

Sandstone

Sandstone (clastic sedimentary rock)

Diamond

Diamond (Carbon, C)

Conglomerate

Conglomerate (a clastic sedimentary rock)

Chert (Flint)

Silicon Dioxide (SiO2)

Mica Schist

Mica Schist (predominantly composed of Muscovite or Biotite silicates)

Red Jasper

Jasper (a variety of 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.

Zebra Jasper

Silicon dioxide (SiO2) with various impurities

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Diorite

Diorite

Limestone

Calcium Carbonate (CaCO3)

Chert (Flint variety)

Chert (Microcrystalline or Cryptocrystalline Quartz), SiO2

Banded Chert

Cryptocrystalline Quartz (SiO2)

Basalt (River Stone)

Aphanitic Mafic Igneous Rock

Basalt

Basalt (extrusive igneous rock)

Greisen (Quartz-Muscovite-Turretine Rock)

Greisen

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Peridot (likely, based on color and appearance)

Olivine group mineral, specifically (Mg,Fe)2SiO4 (Forsterite-Fayalite solid solution series)

Chalcedony (Moonstone variant or White Agate)

Silicon Dioxide (SiO₂)

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Jasper (Imperial Jasper style)

Silicon Dioxide (SiO2) with impurities

Turquoise

Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O

Charoite

Charoite (Hydrated silicate of potassium, sodium, calcium, barium and strontium): (K,Sr,Ba)(Na,Ca)2[Si4O10](OH,f)·H2O

Granite Cobble/Pebble

Granite

Quartzite

Quartzite (primarily SiO2)

Slag (Industrial Byproduct)

Ferrous/Non-ferrous Silicate

Aquamarine

Aquamarine (Beryl variety) - Be3Al2(Si6O18)

Basalt with Mineral Vein (Cobble)

Basalt (with likely Quartz/Calcite vein)

River Rock

Sedimentary Rock (various compositions)

Amazonite

KAlSi3O8 (Potassium Feldspar, variety of Microcline)

Schist

Schist

Chert (specifically Yellow/Brown Chert or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)