Mineraloid (Man Made Origin)

Black Obsidian

Obsidian (Volcanic Glass, ~70% SiO2)

Obsidian

Volcanic Glass (SiO2)

Snowflake Obsidian (Flower Jasper variant)

Vitreous volcanic silicate with cristobalite inclusions

Mahogany Obsidian

Volcanic Glass (Silicate: SiO2 + Fe2O3)

Obsidian

Volcanic Glass (SiO2 rich)

Limonite (with Pyrite)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

Limonite (Ironstone Concretion)

Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)

Diamond (in Jewelry Setting)

Carbon (C)

Limestone

Calcium Carbonate (CaCO3)

Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Carbonado (Black Diamond)

Carbonado (Polycrystalline Diamond)

Obsidian

Obsidian

Fluorite

Calcium Fluoride (CaF2)

Fluorite (Rainbow Fluorite)

Calcium Fluoride (CaF2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Green Fluorite (Fluorite Sphere)

Calcium Fluoride (CaF2)

Peridot

Olivine ((Mg,Fe)2SiO4)

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.

Precious Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Kambaba Jasper

Stromatolite (Fossilized Algae within Microcrystalline Quartz)

Chert (Black Chert)

Microcrystalline Silica (SiO2)

Weathered iron-rich sandstone or lateritic rock

Ferruginous sandstone/laterite; chiefly quartz (SiO₂) with iron oxides such as hematite and goethite

Granite Pebble

Granite (Plutonic Igneous Rock)

Garnet

Garnet Group (formula varies: e.g., Almandine Fe3Al2Si3O12 or Pyrope Mg3Al2Si3O12)

Rough Diamond

Diamond (Native Carbon, C)

Diamond (Faceted)

Carbon (C)

Diamond

C (Carbon)

Basalt Cobble

Aphanitic Mafic Igneous Rock (Basalt)

Corundum

Corundum (Aluminium oxide, Al2O3)

Crushed Limestone

Sedimentary Calcium Carbonate (CaCO3)

Vesicular Basalt (Aqueous Tumbled)

Scoriaceous Basalt

Fluorite

Calcium Fluoride (CaF2)

Green Fluorite

Calcium Fluoride (CaF2)

Fluorite

Calcium Fluoride (CaF2)

Fluorite (Purple variety)

Calcium Fluoride (CaF2)

Fluorite

Calcium Fluoride (CaF2)

Asphalt Pavement (with aggregate)

Asphalt concrete

Blue Slag Glass

Amorphous Silica (Byproduct of smelting)

Cardstock (Paper)

Cellulose (C6H10O5)n

Blue Goldstone

Aventurine Glass (SiO2 with Cobalt/Copper inclusions)

Slag Glass (Cullet)

Amorphous Silicon Dioxide (SiO2) with metal oxide colorants