Organic (If Resin) Or Synthetic (If Glass); Simulating Sedimentary Or Metamorphic (For Natural Stones)

Amethyst

Silicon Dioxide with Iron impurities (SiO2)

Quartz with Pyrite inclusions

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2) inclusions

Basalt with Calcite Veins

Basalt (Mafic Volcanic Rock)

Yellow Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Jasper (Imperial Jasper style)

Silicon Dioxide (SiO2) with impurities

Artificial Rock Face (Faux Rock)

Glass Fiber Reinforced Concrete (GFRC)

Quartz Vein Rock

Silicon Dioxide (SiO2)

Shungite

Non-crystalline carbonoid (Shungite)

Amber

Resinite / Fossilized Tree Resin

Sandstone (Quartz-rich Pebble)

Arenite (primarily SiO2)

Druzy Quartz (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Assorted Semi-Precious Gemstone Crosses

Quartz, Silicates, Carbonates (various)

Sandstone

Arenite (composed primarily of SiO2)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Petoskey Stone (Petrified Favosites)

Favosites (extinct colonial coral), CaCO3 with Silica replacement

Fuchsite Gneiss (Green Quartzite)

Chromium-rich Muscovite (KAl2(AlSi3O10)(OH)2 with Cr replacements)

Amber

Succinite (fossilized resin)

Pebble (likely Quartzite or Chert)

Clastic Sediment, potentially composed of SiO₂ (Quartz)

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Quartzite

Quartzite (SiO2)

Basalt with Jasper Veining

Basaltic Rock with Cryptocrystalline Quartz (SiO2)

Dyed Howlite (simulating Lavender/Purple Jade or Charoite)

Howlite: Ca2B5SiO9(OH)5 (when natural)

Chert (Quartzite-rich River Pebble)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (with Goethite/Limonite cement)

Garnet (Almandine)

Almandine, Fe3Al2(SiO4)3

Sandstone or Mudstone

Sedimentary Rock (Sandstone/Mudstone)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Moqui Marble (Moqui Ball)

Ironstone Concretion (Goethite/Hematite cemented Sandstone)

Pyrite

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.

Red Sandstone

Arenite (predominantly SiO2 with Fe2O3)

Sandstone (Quartzite-rich Cobble)

Clastic sedimentary rock (primarily SiO2)

Quartz Geode / Druzy Quartz

Silicon Dioxide (SiO2)

Blue Apatite

Apatite-(CaF), Ca5(PO4)3F

Amethyst

Silicon Dioxide with trace Iron (SiO2)

Chalcedony (specifically Agate or Carnelian pebble)

Chalcedony (Microcrystalline Quartz, SiO2)

Garnet (specifically Almandine)

Almandine - Fe3Al2(SiO4)3

Chert (Nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Quartzite pebble

Quartzite (SiO2 dominated)

Sandstone

Arenite (SiO2 based with various mineral cements)

Mica Schist

Mica Schist (predominantly Muscovite or Biotite sheet silicates)