Rock (Likely Sedimentary)

Bauxite

Al2O3·2H2O (principally composed of gibbsite, boehmite, and diaspore)

Sandstone (Pebble)

Clastic sedimentary rock (SiO2 primary)

Jasper (Mookaite variety likely)

Silicon Dioxide (SiO2) with iron oxide inclusions

Jasper (likely river-worn)

Silicon Dioxide (SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (Quartzose type)

Arenite (primarily SiO2)

Chert (Jasper/Iron-stained Quartzite)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Sandstone

Arenite (composed primarily of Quartz: SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Conglomerate with Native Copper

Clastic Sedimentary Rock with Native Copper (Cu)

Blue Apatite

Apatite - Ca5(PO4)3(F,Cl,OH)

Limestone

Calcium Carbonate (CaCO3)

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Dalmatian Stone

Dalmatian Jasper (Aplitic Rock)

Limonitic Sandstone with Inclusion

Limonitic Quartz Sandstone (primarily SiO2 with FeO(OH)·nH2O)

Sandstone Pebble

Arenite (primarily Quartz, SiO2)

Sandstone (Ferruginous)

Arenite with Iron Oxides

Gneiss

Gneiss

Carnelian (Chalcedony)

Silicon Dioxide (SiO2)

Sandstone (specifically an Iron-Concretion)

Arenite with Iron Oxide (Limonite/Goethite) cementation

Microcrystalline Limestone Pebble

Carbonate sedimentary rock (Calcium Carbonate, CaCO3)

Sandstone

Arenite (composed primarily of Quartz, SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Limestone

Sedimentary Calcite (CaCO3)

Satin Spar (Gypsum)

Hydrous Calcium Sulfate (CaSO4·2H2O)

Quartz Vein in Host Rock

Quartz (SiO2) in Mafic or Sedimentary Matrix

Sandstone

Arenite (SiO2 based with various cements)

Conglomerate

Conglomerate rock

Chert (Nodular)

Microcrystalline Silica (SiO2)

Quartz / Common Agate

Silicon Dioxide (SiO2)

Chalcedony

Silicon Dioxide (SiO2)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Banded Chert (Agate)

Silicon Dioxide (SiO2)

Specular Hematite

Iron Oxide (Fe2O3)

Kambaba Jasper (Crocodile Jasper)

Rhyolite containing Fossilized Cyanobacteria (Stromatolite)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chalcedony (Agate/Carnelian)

Cryptocrystalline Silicon Dioxide (SiO2)

Blue Chalcedony

Chalcedony (SiO2)

Bituminous Coal

Bituminous coal (Carbonaceous sedimentary rock)

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.