Anthropogenic (Human Made) Sedimentary Like Material

Sandstone

Arenite (primarily SiO2)

Aventurine (specifically Green Aventurine)

Silicon Dioxide (Quartz) with inclusions of Fuchsite; SiO2 + K(Al,Cr)2AlSi3O10(OH)2

Snowflake Obsidian

Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)

Halite (Rock Salt)

Halite (Sodium Chloride, NaCl)

Diorite

Diorite

Red Jasper

Red Jasper (variety of Chalcedony, SiO₂)

Gold

Aurum (Au)

Moss Agate

Silicon Dioxide (SiO2) with mineral inclusions of hornblende or chlorite

Sandstone

Clastic sedimentary rock (primarily SiO2)

Sandstone (Ferruginous)

Arenite (Fe-rich)

Quartzite

Quartzite (primarily SiO2)

Sandstone (likely with Quartz Veining)

Arenite (primarily SiO2)

Sandstone

Arenite (primarily Quartz, SiO2)

Barite

Barium Sulfate (BaSO4)

Potassium Feldspar and Quartz

KAlSi3O8 (Potassium Feldspar) and SiO2 (Quartz)

Blue Chalcedony

Silicon Dioxide (SiO2)

Limestone (specifically Fossiliferous Limestone)

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Rough Emerald

Beryl (Be3Al2(SiO3)6 with Chromium/Vanadium impurities)

Banded Iron Formation (BIF) with Quartz

Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)

Green Jasper

Silicon Dioxide (SiO2) with mineral inclusions

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 (Quartzose)

Arenite (predominantly SiO2)

Chalcedony (Common Opal variant)

Silicon dioxide (SiO2) with varying levels of hydration

Obsidian

Volcanic glass

Sandstone with Iron Oxide (Limonite/Hematite)

Ferruginous Sandstone (SiO2 with FeO(OH)·nH2O)

Sandstone (likely Arkose or Quartz Sandstone)

Arenite (SiO2 + varied clasts)

Diorite

Diorite (Intermediate intrusive igneous rock)

Blue Goldstone

Aventurine glass (Synthetic borosilicate glass with cobalt and metallic inclusions)

Sandstone (Ferruginous)

Arenite with Iron-oxide inclusions (SiO2 primarily)

Ferruginous Sandstone

Arenite with Iron-Oxide Cement (SiO2 with Fe2O3/FeO(OH))

Serpentinite (often containing Jadeite/Nephrite)

Antigorite-rich Serpentine Rock, (Mg, Fe)3Si2O5(OH)4

Chert (Nodule)

Microcrystalline quartz (SiO2)

General Rock and Mineral Collection (Center: Angelite / Blue Anhydrite)

Anhydrite (Calcium Sulfate, CaSO4)

Limonite / Ironstone Nodule

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

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Cinnabar

Mercury(II) sulfide (HgS)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Basalt

Aphanitic Mafic Igneous Rock

Quartz

Quartz (SiO2 - Silicon Dioxide)

Hematite

Hematite (Fe2O3)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)