Mineral Precipitate (Anthropogenic Context)

Sandstone Concretion with Quartz Center

Sedimentary Clastic Rock (SiO2 matrix with Quartz core)

Chrysocolla on Matrix

Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4·nH2O

Sandstone

Clastic sedimentary rock (primarily SiO2)

Calcite (Yellow/Orange variety - sometimes called Honey Calcite)

Calcite

Red Sandstone

Arenite (Ferruginous Sandstone)

Raw Green Jasper

Silicon Dioxide (SiO2) with iron silicate inclusions

Milky Quartz with Mineral Inclusions

Quartz (Silicon Dioxide, SiO2)

Silver (Native Silver Mineral)

Ag (Native Silver), Alloyed 90% Ag / 10% Cu

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

Anhydrite (Calcium Sulfate, CaSO4)

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

Pearl (as a biogenic mineral/gemstone)

Calcium Carbonate (mostly Aragonite), CaCO3

Agate

Agate (Silicon Dioxide, SiO2)

Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')

Calcite (Calcium Carbonate, CaCO3)

Lepidolite

K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2

Chrysocolla in Matrix

Chrysocolla (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O)

Turquoise in Matrix

CuAl6(PO4)4(OH)8·4H2O (Hydrous phosphate of copper and aluminium)

Schist (Micaceous)

Mica Schist

Citrine

SiO2 (Silicon Dioxide)

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety, likely a orthogneiss or paragneiss depending on parent rock)

Fluorite (Rainbow or Multi-colored Fluorite)

Fluorite (Calcium Fluoride - CaF2)

Turquoise and Hematite

CuAl6(PO4)4(OH)8·4H2O (Turquoise) and Fe2O3 (Hematite)

Sandstone (likely with Quartz Veining)

Arenite (primarily SiO2)

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.

Hematite

Hematite (Fe2O3)

Fluorite (Rainbow/Purple Fluorite)

Calcium Fluoride (CaF2)

Slate

Foliated Metamorphic Rock (primarily composed of quartz, illite, chlorite, and micas)

Granite

Granite

Pyrite

Iron Disulfide (FeS2)

Lapis Lazuli

A metamorphic rock primarily composed of lazurite (Na,Ca)8[(S,SO4,Cl)2|(Al6Si6O24)], calcite (CaCO3), and pyrite (FeS2).

Biotite Schist

Biotite Schist

Red Jasper

Silicon Dioxide with Iron Oxide (SiO2)

Greywacke

Dirty Sandstone (Lithic wacke)

Coarse Sandstone

Arenite (SiO2 based)

Chrysocolla

Chrysocolla (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O)

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic extrusive volcanic rock with secondary mineral infilling)

Schist with Biotite and Quartz

Biotite-Quartz Schist (Fe,Mg,Al silicate mix)

Yellow Ochre / Limonite

Limonite (FeO(OH)·nH2O)

Orthoclase Feldspar

Potassium aluminum silicate (KAlSi3O8)

Limonite (Iron Stone/Gossen)

Limonite (FeO(OH)·nH2O)

Limonite

Limonite (Hydrated iron oxide mixture, FeO(OH)·nH2O)

Granite

Granite

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)