Industrial Byproduct (Anthropogenic Rock Like Material)

Petrified Wood

Silicified Wood (SiO2)

Veined Quartz

SiO2 (Silicon Dioxide)

Ruby (Raw Corundum)

Corundum (Aluminum Oxide with Chromium), Al2O3:Cr

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2)

Fossiliferous Limestone

Carbonate sedimentary rock (CaCO3)

Basalt

Basalt

Sandstone (with potential Arkose/Lithic characteristics)

Arenite (Sedimentary rock composed of sand-sized grains)

Banded River Pebble (Gneiss or Quartz-Veined Basalt)

Polished River Siltstone or Quartzite Gneiss

Granite

Phaneritic Felsic Igneous Rock

Chert

Microcrystalline Quartz (SiO2)

Tufa

Calcareous Tufa (CaCO3)

Chert / Flint

Silicon Dioxide (SiO2)

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Terrazzo (Man-made Composite)

Cementitious or Resin-bound Lithic Composite

Basalt

Basalt

Basalt with Plagioclase Phenocrysts

Porphyritic Basalt

Mica (Muscovite)

Muscovite (KAl2(AlSi3O10)(OH)2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Quartzite River Pebble

Metamorphosed Quartz Sandstone (SiO2)

Bauxite

Bauxite (Al(OH)3, AlO(OH))

Crushed Limestone

Sedimentary Calcium Carbonate (CaCO3)

Seraphinite

Clinochlore (Mg,Fe)5Al(AlSi3O10)(OH)8 - specific variety for Seraphinite due to its fibrous inclusions and chatoyancy.

Chert (often called Flint or Jasper based on color)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Granitic Pegmatite with Schorl

Granitic Pegmatite (NaAlSi3O8, KAlSi3O8, SiO2) with Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

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 Druze on Matrix

Silicon Dioxide (SiO2)

Black Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Orange Quartzite / Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions

Banded Chert (River Stone)

Silicon Dioxide (SiO2)

Basalt (River Pebble)

Basalt

Basalt

Basalt

Blue Sapphire

Corundum (Al2O3 with trace Titanium and Iron)

Pink Granite

Granite (Felsic plutonic rock)

Decomposed Granite

Grano-diorite/Granite-residuum (SiO2 primary)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Glacial Quartzite Cobble

Meta-orthoquartzite (SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Granite

Granite (felsic intrusive igneous rock)

Serpentinite

Serpentinite (composed primarily of minerals in the Serpentine group)