Man Made Material (Simulated Mineral)

Red Sandstone

Arenite (Fe2O3 rich)

Black Sapphire (Basaltic Blue Sapphire)

Corundum (Al2O3)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Diamond

Diamond (pure Carbon, C)

Sandstone (specifically Red Sandstone)

Arenite (SiO2 with Iron Oxide)

Sandstone (Quartz-rich)

Clastic sedimentary rock (SiO2 primary)

Siltstone

Siltstone (primarily composed of SiO2 with various clay minerals)

Diamond

C (Carbon)

Mother of Pearl and Onyx

Aragonite (Mother of Pearl) and Chalcedony (Onyx)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Petrified Wood

Silicified Wood (primarily SiO2)

Coral Fossil (Petrified Coral)

Scleractinia (Order) - Calcified Fossil Skeleton (CaCO3)

Petrified Wood

Silicified Wood (primarily Quartz / Chalcedony: SiO2)

Chondrite Meteorite

Ordinary Chondrite (L or H Type)

Sandstone (with Iron Oxide)

Arenite with Limonite/Hematite staining

Zebra Jasper

Tumbled Opaque Chalcedony (SiO2)

Diorite (River Cobble)

Intermediate plutonic igneous rock

Red Sandstone

Arenite (with Iron Oxide / Hematite), Formula: SiO2 (Quartz) + Fe2O3 (Hematite coating)

Milky Quartz

Silicon Dioxide (SiO2)

Snowflake Obsidian

Volcanic glass containing Spherulitic Cristobalite (SiO2)

Quartzite

Quartzite (primarily SiO2)

Banded Gneiss (River Cobble)

Gneiss (a high-grade metamorphic rock)

Diamond (Princess Cut)

Carbon (C)

Chondrite Meteorite

Ordinary Chondrite (Fe-Ni alloy, Olivine, Pyroxene)

Pyrite (Iron Pyrites)

Iron Sulfide (FeS2)

Coquina / Shelly Limestone

Coquina (calcium carbonate, CaCO3)

Petrified Wood

Silicified Wood (SiO2)

Plagioclase Feldspar

NaAlSi3O8 – CaAlSi2O8 (Sodium-Calcium Aluminum Silicates)

Pyrite

Iron Sulfide (FeS2)

Turquoise

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

White Quartz Pebble

Silicon Dioxide (SiO2)

Olivine (often within Peridotite)

Magnesium iron silicate, (Mg,Fe)2SiO4

Labradorite

Labradorite ((Ca, Na)(Al, Si)4O8)

Orange Calcite (Carved as a Horned Skull)

Calcium Carbonate (CaCO3)

Sandstone

Sandstone (clastic sedimentary rock)

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Red Sandstone

Arenite (with Iron Oxide / Hematite cementation)

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.

Sandstone

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

Red Sandstone

Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)