Mineral (Synthetic)

Covellite

Covellite (CuS)

Schist (Micaceous)

Mica Schist

Red Sandstone

Arenite (primarily Quartz with Iron Oxide coating)

Tree Agate

Silicon dioxide (SiO2)

Greenstone (Amygdaloidal Basalt)

Amygdaloidal Basalt (frequently composed of Plagioclase Feldspar, Pyroxene, and Olivine with Chlorite inclusions)

Quartz (Milky/Rose variety)

Silicon Dioxide (SiO2)

Glaucophane-bearing Schist (Blueschist)

Blueschist (Glaucophane-Lawsonite Schist)

Pink Granite

Granite (Phaneritic Quartz-Feldspar Rock)

Gneiss

Gneiss

Granodiorite (or Granite) Pebble

Phaneritic Felsic Igneous Pebble

Sandstone Concretion with Quartz Center

Sedimentary Clastic Rock (SiO2 matrix with Quartz core)

Emerald in Host Rock

Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities

Citrine

SiO2 (Silicon Dioxide)

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock)

Fluorite (Rainbow or Multi-colored Fluorite)

Fluorite (Calcium Fluoride - CaF2)

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Granite

Granite

Limonite Geode (Ironstone Concretion)

Limonite [FeO(OH)·nH2O] with possible Quartz or Calcite interior

Quartz Geode

SiO2 (Silicon Dioxide)

Turquoise and Hematite

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

Red Sandstone (Iron-rich)

Ferruginous Sandstone (SiO2 with Iron Oxides)

Quartz-veined Sedimentary Rock

Hydrothermally veined Clastic Sedimentary Rock (SiO2 veins in Matrix)

Sandstone (likely with Quartz Veining)

Arenite (primarily SiO2)

Sandstone

Arenite (lithic or quartz sandstone)

Epidosite

Epidosite (Metasomatic rock consisting mainly of Epidote and Quartz)

Lapis Lazuli

Na6Ca2(Al6Si6O24)(S,SO4,Cl)1-2 (primarily containing Lazurite with inclusions of Calcite and Pyrite)

Amygdaloidal Basalt

Vesicular-Amygdaloidal Basalt (Mafic Extrusive)

Turquoise in Matrix

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

Malachite

Copper carbonate hydroxide [Cu2CO3(OH)2]

Fluorite (likely Fluorite on Quartz/Matrix)

Calcium Fluoride (CaF2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Orthoclase Feldspar

Orthoclase (KAlSi₃O₈)

Bumblebee Jasper

Anhydrite with Sulfur, Hematite, and Orpiment (SiO2/CaSO4 mixture)

Lapis Lazuli

Lapis Lazuli (Rock composed primarily of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)

Chrysocolla

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

Schist with Biotite and Quartz

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

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

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.

Malachite

Malachite (Copper Carbonate Hydroxide, Cu2CO3(OH)2)

Lapis Lazuli (Raw)

Lazurite-rich metamorphic rock; Na3Ca(Al3Si3O12)S

Educational Geologic Collection

Mixed Mineral and Rock Collection (Various compositions)

Slate

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