Sedimentary Rock (Possibly Conglomerate Or Breccia With A Quartz Vein)

Weathered limestone or calcareous fossil fragment

Calcite-rich carbonate rock (CaCO₃), possibly fossiliferous limestone

Jasper Pebble

Microcrystalline Quartz (SiO2)

Mixed polished river stones

Likely quartz, quartzite, chert/jasper, and possibly limestone or marble

Chalcedony Geode

Silicon Dioxide (SiO2)

Leopard Skin Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Basalt with Quartz/Feldspar Vein

Amygdaloidal Basalt with Plutonic intrusion (SiO2/KAlSi3O8)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Silicon Dioxide (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 (Rock Crystal)

Silicon Dioxide (SiO2)

Mixed rounded stream pebbles

Most appear to be granitic and mafic igneous rocks, including granite, gneiss, basalt, and possibly quartzite; exact identification is uncertain from the image.

Banded Gneiss / Veined Metamorphic Pebble

Metamorphic Rock with Quartz/Feldspar Veins

Brecciated Jasper

SiO2 (Silicon Dioxide)

Druzy Quartz on Limestone

Silicon Dioxide (SiO2) on Calcium Carbonate (CaCO3)

Quartzite with Quartz Veining

Metamorphic Quartzite (SiO2)

Weathered limestone or calcareous sandstone

Likely micritic limestone (calcite, CaCO₃), possibly carbonate-rich sandstone

Quartz (Microcrystalline/Gravel)

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Sandstone (Common Quartz Pebble/Rock)

Sedimentary rock / Quartz arenite

Clear Quartz

Silicon dioxide (SiO2)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Red Jasper (possibly Red Coral or dyed Howlite)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Quartz (Milky and Bull Quartz)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Milky or Cloudy)

Silicon Dioxide (SiO2)

Agate Geode

Silicon Dioxide (SiO2) - Chalcedony variety

Quartz

Quartz (SiO₂)

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Milky Quartz/Citrine Type)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz Geode with Calcite

Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3)

Blue quartz-like mineral specimen

Likely quartz (SiO₂), possibly dyed or coated; exact identification requires testing

Druzy Quartz on Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Pyrite in Matrix (Quartz/Schist)

Iron Sulfide (FeS2)

Ocean Jasper (Orbicular Jasper)

Silicon Dioxide (SiO2) with iron and other mineral inclusions

Quartz-rich sandstone or quartzite fragment

Likely quartz arenite; possibly weakly metamorphosed quartzite (mostly SiO₂)

Quartz River Pebble

Silicon Dioxide (SiO2)

Quartz (Druzy or Crystalline)

Silicon Dioxide (SiO2)