Igneous Or Metamorphic (Base Stone); Anthropogenic (Decoration)

Jasper

Silicon dioxide (SiO2)

Biotite / Black Mica

K(Mg,Fe)3(AlSi3O10)(F,OH)2

Blue Sapphire

Corundum (Al2O3)

Graphite

Graphite (Native Carbon), Formula: C

Slag (Industrial Glass)

Artificial Vitreous Silicate

Gneiss (with Quartz and Biotite Mica)

Gneiss

Gneiss

Gneiss (High-grade metamorphic rock)

Aventurine

Aventurine Quartz (SiO2 with inclusions)

Chert (often called Flint)

Chert (Microcrystalline Quartz, SiO2)

Peacock Ore (Bornite or Chalcopyrite treated with acid)

Bornite (Cu5FeS4) or Acid-washed Chalcopyrite (CuFeS2)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Biotite (Mica)

Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2

Muscovite Mica

Muscovite (Potassium Aluminum Silicate) - KAl2(AlSi3O10)(F,OH)2

Biotite (Mica)

Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)

Mica-rich Pegmatite

Pegmatite (rich in Muscovite and Biotite)

Gold Mineral

Native Gold (Au)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(F,OH)2)

Granite Cobble

Granite (Phaneritic Quartz-Feldspar Felsic Rock)

Black Tourmaline (Schorl)

Schorl (Sodium iron silicate hydroxide boron silicate); NaFe3Al6(BO3)3Si6O18(OH)4

Peacock Ore

Bornite (Cu5FeS4) or iridescent Chalcopyrite (CuFeS2)

Muscovite Mica

KAl2(AlSi3O10)(F,OH)2

Map Jasper (Picasso Stone)

Metamorphosed Calcium Carbonate (Crystalline Limestone or Marble with Silicate inclusions/impurities)

Schist

Mica Schist (formula variable based on mineral content, typically containing [K,Al,Fe,Mg,Si,O,H])

Epidote

Epidote; Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

Venetian Gold Granite

Phaneritic Felsic Igneous Rock (Granite)

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.

Slag

Ferrous slag (by-product of iron smelting)

Biotite Mica

K(Mg,Fe2+)3(Al,Fe3+)Si3O10(OH,F)2

Quartz with Mica (Gneissic or Pegmatitic origin)

Silicon Dioxide (SiO2) with Phyllosilicates (KAl2(AlSi3O10)(F,OH)2)

Granite Pebble

Granite (Phaneritic intrusive igneous rock)

River Stone (Basalt Porphyry)

Porphyritic Basalt

Rough Agate/Chert Nodules

Cryptocrystalline Quartz (SiO2)

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Muscovite Mica

Muscovite: KAl2(AlSi3O10)(OH)2

Epidote

Epidote (formula: Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Grey Quartz (likely Smoky Quartz or Milky Quartz)

Silicon Dioxide (SiO2)

Geode with Iron-Stained Quartz/Calcite

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) in Sedimentary Matrix

Muscovite Mica

Muscovite (Potassium Mica) KAl2(AlSi3O10)(OH)2

Chlorite (Small Flakes/Sand)

Chlorite Group (Magnesium Iron Aluminum Silicate Hydroxide - (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6)