Not A Natural Rock (Man Made Composite)

Carnelian

Carnelian (a variety of Chalcedony, SiO2)

Moonstone (specifically Cat's Eye or Gray Moonstone)

Orthoclase (Potassium Aluminum Silicate) with the formula (K,Na)AlSi3O8

Pink Thulite (Zoisite)

Ca2Al3(SiO4)3(OH) - Manganese-bearing Zoisite

Dendritic Opal

Dendritic Common Opal (SiO2·nH2O with Manganese oxide inclusions)

Quartzite

Quartzite (primarily SiO2)

Granite (likely a river or beach pebble)

Granite (a felsic intrusive igneous rock primarily composed of quartz, feldspar, and mica)

Chalk

Calcium Carbonate (CaCO3)

Bauxite (Aluminum Ore)

Hydrated aluminum oxides, primarily Al(OH)3, AlO(OH)

Sandstone (likely Quartz Sandstone)

Arenite (composed primarily of SiO2)

Turquoise with Pyrite

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O] with Iron Pyrite (FeS2)

Gold and Diamond

Native Gold (Au) and Diamond (C)

Iron Meteorite

Iron-nickel alloy (primarily kamacite and taenite)

Smurf Rock (Fictional Interpretation)

Cyanus Anthropomorphicus (Geologic Simulation)

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.

Quartzite pebble

Quartzite (SiO2)

Black Diamond / Black Sapphire

Carbon (C) or Corundum (Al2O3)

Quartzite

Quartzite (SiO2)

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Bauxite

Bauxite (mixture of hydrous aluminum oxides: Al(OH)3 & AlO(OH))

Moss Agate

Chalcedony (Silicon Dioxide - SiO2) with inclusions

Fluorite (Rainbow Fluorite Point)

Calcium Fluoride (CaF2)

Green Moss Agate

Agate (Silicon Dioxide, SiO2) with inclusions of hornblende or chlorite

Rose Quartz

Rose Quartz (SiO2)

Pink Granite

Phaneritic Plutonic Felsic Rock (K-feldspar rich)

Garnet-Bearing Gneiss

Almandine-Garnet Gneiss

Bauxite

Alumina-rich rock (consisting of Gibbsite, Boehmite, and Diaspore)

Quartz (Milky Quartz)

Quartz (SiO2 - Silicon Dioxide)

Moss Agate

Silicon Dioxide (SiO2) with mineral inclusions

Blue Agate (Dyed)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Silty Sand / Loam

Unconsolidated Clastic Sediment (Silicon Dioxide / Alumino-silicates mixture)

Limestone

Calcium Carbonate (CaCO3)

Tree Agate (also known as Dendritic Agate)

Silicon Dioxide with inclusions (SiO2 + Mn/Fe)

Limonite (Iron Ore)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Dyed Blue Agate

Cryptocrystalline Quartz (SiO2)

Rhodonite

Rhodonite (Manganese silicate), (Mn,Fe,Mg,Ca)SiO3

Moonstone

Orthoclase (Potassium aluminum silicate - KAlSi3O8)

Sunstone

Plagioclase Feldspar (Na,Ca)(Al,Si)4O8

Ruby

Corundum (Al₂O₃) with Chromium (Cr)

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartzite with Sandstone/Iron staining

Metamorphic Quartzite (SiO2)

Tree Agate

Dendritic Chalcedony (SiO2)