Metamorphic Rock (For Both Nephrite And Jadeite)

Clear Quartz

Silicon Dioxide (SiO2)

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Greenschist

Greenschist facies rock (containing chlorite, actinolite, and epidote)

Eclogite

Eclogite (Omphacite + Almandine-Pyrope Garnet)

Quartzite (River Stone)

Quartzite

Clear Quartz

Silicon Dioxide (SiO2) / Rock Crystal

Rough Dark Green Sapphire

Corundum (Al2O3)

Epidosite (Epidote-rich rock)

Epidotalite (primarily Ca2(Al2Fe3+)(SiO4)(Si2O7)O(OH))

Schist (Micaceous Schist)

Schist (containing mainly Muscovite and Quartz)

Quartzite

Quartzite (SiO2)

Yellow Quartzite (River Pebble)

Quartzite (mainly SiO2)

Yellow Quartzite (River Stone)

Quartzite (primarily SiO2)

Quartzite (specifically a river-worn cobble)

Quartzite (primarily Silicon Dioxide, SiO2)

Quartzite with Iron Hydroxide Staining

Quartzite (primarily SiO2) with Limonite/Goethite staining

Serpentinite

Serpentinite (containing minerals of the Serpentine subgroup: Antigorite, Lizardite, and Chrysotile; formula (Mg,Fe)3Si2O5(OH)4)

Schist

Mica Schist

Quartzite Pebble

Quartzite (primarily SiO2)

River Pebbles and Quartz

Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)

Unakite

Epidotized Granite

River Pebble (Quartzite/Sandstone mix)

Quartzite (primarily SiO2)

Lapis Lazuli

Na8(Al6Si6O24)S2 (composed primarily of Lazurite, Calcite, and Pyrite)

Quartzite Pebble

Quartzite (primarily SiO2)

Garnet in Matrix (likely Almandine in Quartz/Mica Schist)

Almandine Garnet (Fe3Al2(SiO4)3) in Quartz-Feldspar host rock

Quartzite Pebble

Quartzite (SiO2)

Quartzite with Quartz Vein

Quartzite (SiO2)

Serpentine

Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Quartzite (Tumbled Pebble)

Metamorphosed Quartz Sandstone (SiO2)

Quartzite Pebbles

Quartzite (SiO2 silicon dioxide dominant)

Riverstone Quartzite (Water-worn Siltstone/Quartzite)

Metamorphosed Quartz-rich Arenite (SiO2)

Quartzite River Rock

Quartzite (SiO2)

Smoky Quartz (Vein Quartz)

Quartz (Silicon Dioxide, SiO2)

Mica Schist

Mica Schist (Complex Silicate Rock)

Quartzite with Chert inclusions

Metamorphosed Quartz-rich Rock (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.

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Citrine Geode Fragment

Citrine (Silicon Dioxide with Iron Impurities), SiO2

Slate

Slate (Foliated metamorphic rock consisting mainly of quartz and muscovite or illite)

Slate

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

Quartzite Pebble (River Rock)

Metamorphic Quartzite (predominantly SiO2)

Rough Garnet in Matrix

Almandine Garnet (Fe3Al2Si3O12)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Petrified Wood

Silicified Wood (SiO2)