Mineral Description (Anthropogenic Material)

Sedimentary Breccia

Breccia (Clastic Sedimentary Rock)

Sandstone

Arenite (SiO2 based with various mineral cements)

Sandstone

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

Kyanite

Kyanite (Al2SiO5)

Sandstone

Arenite (a specific type of sandstone with less than 15% matrix)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Blue Aventurine

Silicon Dioxide (SiO2) with inclusions of Dumortierite

Goldstone (with Tiger's Eye and Quartz)

Aventurine glass (Synthetic SiO2 with Cu inclusions)

Sandstone

Quartz Sandstone (predominantly)

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pyrite

Iron Disulfide (FeS2)

Turquoise

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Milky Quartz

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Diorite (Salt and Pepper Rock)

Phaneritic plutonic igneous rock (sodium-rich plagioclase feldspar and hornblende)

Banded Iron Formation (BIF) with Quartz

Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)

Diorite

Intermediate plutonic igneous rock

River Cobble (Basaltic/Andesitic)

Mafic Igneous Porphyritic Rock

Chalcedony (specifically Agate or Flint)

Silicon Dioxide (SiO₂)

Fossil Coral (Petoskey Stone or Favosites)

Favosites (specifically Hexagonaria percarinata if silica-replaced Michigan type)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (and Jasper/Flint variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Synthetic Wolf Plush (Non-mineral)

Canis lupus similis (Prop material: Polyester & Synthetic fibers)

Turquoise

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

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.

Chert (often colloquially called Flint)

Chert (Microcrystalline Quartz, SiO2)

Sandstone or Limestone

Sedimentary Rock

Diamond

Diamond (C)

Black Obsidian

Volcanic Glass (predominantly SiO2, Silicon Dioxide)

Goldstone (Synthetic Aventurescence Glass)

Cuprous Aventurescent Glass (Silicon Dioxide with Copper inclusions)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Quartz (Water-worn pebble)

Silicon Dioxide (SiO2)

Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Mica Schist

Mica Schist (contains Muscovite/Biotite, Quartz)

Petrified Wood

Silicified Wood (primarily SiO2)

Petrified Wood

Silicified Wood (SiO2)

Banded Chert

Silicon Dioxide (SiO2)

Flint / Chert

Silicon dioxide (SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2) - Microcrystalline Quartz