Mineral Based Composite

Otodus Shark Tooth

Otodus obliquus

Opalite crescent pendant

Opalite (man-made opalescent glass; not a natural mineral)

Painted Sandstone

Sandstone (clastic sedimentary rock) with acrylic/artistic coating

Banded Onyx (Mexican Onyx / Travertine)

Calcite (CaCO3) - Banded Travertine

Sandstone

Arenite (SiO2 dominant)

Sandstone (Quartz Sandstone / Iron-stained Sandstone)

Sandstone (SiO2 with iron oxide impurities)

Dendritic sandstone

Sandstone with Manganese Oxide dendrites

Que Sera Stone (Llanite with Feldspar and Quartz)

Rhyolite with blue quartz and pink orthoclase (Llanite-type quartz porphyry)

Rose Quartz

Silicon dioxide (SiO2) with traces of titanium, iron, or manganese

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Engineerged Quartz (Quartz Composite)

SiO2 (Silicon Dioxide) in a polymer resin matrix

Moss Agate

Silicon Dioxide (SiO2) with Chlorite/Hornblende inclusions

Bumblebee Jasper

Anhydrous Calcium Carbonate with Sulfur and Arsenic (Orpiment/Realgar)

River Pebble

Quartzite / Weathered Sedimentary Rock

Tumbled orbicular jasper

Orbicular jasper; microcrystalline quartz (SiO₂) with iron oxides and feldspathic/chalcedony inclusions

Muscovite Mica

Muscovite KAl2(AlSi3O10)(OH)2

Pebble

Lithified clastic rock fragment / Quartz-rich pebble

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

Arenite

Sandstone (with potential trace fossils)

Clastic sedimentary rock (primarily SiO2)

Blue Quartzite

Quartzite (silicon dioxide, SiO2)

Green Moss Agate

Silicon Dioxide (SiO2) with Mineral Inclusions

Granite

Granite (Phaneritic Igneous Rock)

Cubic Zirconia

Zirconium Dioxide (ZrO2)

Blue Kyanite

Kyanite (Al2SiO5)

Moss Agate

Silicon Dioxide (SiO2) with inclusions

Dendritic Agate

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Blue Sapphire

Corundum (Al2O3)

Gold Nugget Jewelry

Native Gold (Au)

Sandstone (Quartzose)

Arenite (SiO2 based typically)

Unakite

Altered Granite (Epidotized Granite)

Iron Slag

Anthropogenic Iron oxide/Silicate composite

Sandstone

Arenite (SiO2 primarily)

Quartz-rich gravel fragment

Quartz (silicon dioxide, SiO₂), possibly with feldspar or carbonate inclusions

Chert (Cream Variety)

Microcrystalline silica (SiO2)

Unakite

Altered granite (Epidote, Orthoclase Feldspar, and Quartz)

Mixed Mineral Collection (Quartz, Amethyst, Rose Quartz, Pyrite, etc.)

Mixed Silicates and Sulfides (SiO2, FeS2)

Schist

Schist (Crystalline Metamorphic Rock)

Sandstone (River Rock)

Arenite (SiO2 based sedimentary rock)

Sandstone Pebble

Arenite (SiO2 with minor mineral cements)

Quartz Pebble

Silicon Dioxide (SiO2)

Purple Turquoise (Composite Mojave Turquoise)

CuAl6(PO4)4(OH)8·4H2O (Hydrated copper aluminum phosphate composite)