Mineral (Chalcedony)

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

Calcite

Sandstone Concretion with Quartz Center

Sedimentary Clastic Rock (SiO2 matrix with Quartz core)

Garden Quartz (Lodalite)

Silicon Dioxide (SiO2) with mineral inclusions

Limonite (Ironstone)

Limonite (mixture of hydrated iron(III) oxide-hydroxides)

Bauxite

Bauxite (Al2O3·2H2O mixed with iron oxides)

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)

Shale or Slate with Quartz Veins

Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins

Turquoise in Matrix

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

Gneiss

High-grade regional metamorphic rock (Foliated)

Slate

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

Granite

Granite

Granite

Granite (Felsic intrusive igneous rock)

Desert Rose

Gypsum (variety Selenite) or Barite: CaSO4 · 2H2O

Granite

Granite

Jadeite and Mixed Gemstones (Ruby, Sapphire, Emerald)

Jadeite (NaAlSi2O6), Corundum (Al2O3), Beryl (Be3Al2(Si6O18))

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.

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

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

Fluorite (left), Sodalite (middle), Dumortierite/Tumbled Quartzite (right)

Calcium Fluoride (CaF2), Sodium Aluminum Silicate Chloride (Na8(Al6Si6O24)Cl2), Aluminum Borosilicate (Al7(BO3)(SiO4)3O3)

Quartz Geode

Silicon dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Green Fluorite

Calcium Fluoride (CaF2)

Schist with Biotite and Quartz

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

Fluorite (Rainbow/Purple Fluorite)

Calcium Fluoride (CaF2)

Fluorite (Polished Point/Tower)

Calcium Fluoride (CaF2)

Granite

Granite

Pebble

Clast (specifically a granule or small pebble)

Granitic Gneiss

Gneiss (Complex silicate composition)

Calcite

Calcite (Calcium Carbonate, CaCO3)

Milky Quartz with Mineral Inclusions

Silicon Dioxide (SiO2)

Quartz in Matrix (possibly Basalt or Siltstone host)

Silicon Dioxide (SiO2) in Host Rock

Quartz (Druzy)

Silicon Dioxide (SiO2)

Lapis Lazuli

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

Lapis Lazuli (Raw)

Lazurite-rich metamorphic rock; Na3Ca(Al3Si3O12)S

Amygdaloidal Basalt

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