Igneous Or Metamorphic

Pebble (likely Quartz or Chert)

SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.

Sunstone and Green Aventurine

Sunstone: (Ca,Na)[(Al,Si)2Si2O8] (Plagioclase Feldspar Group); Green Aventurine: SiO2 (Quartz)

Baroque Pearl (and potentially a small Sapphire/Blue Topaz)

Pearl: Calcium Carbonate (aragonite or calcite) with conchiolin. Sapphire: Aluminum Oxide (Al2O3). Blue Topaz: Al2SiO4(F,OH)2.

Green Aventurine and Clear Quartz

Green Aventurine (Silicon Dioxide - SiO2 with Fuchsite inclusions); Clear Quartz (Silicon Dioxide - SiO2)

Aventurine (likely Green Aventurine)

Quartz (SiO2) with included minerals (Fuchsite or Chlorite for green color)

Green Aventurine

Quartz (SiO2) with Fuchsite inclusions

Rutilated Quartz (likely Citrine or Smoky Quartz with Rutile inclusions)

SiO2 with TiO2 inclusions (Quartz with Rutile)

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.

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

Mixed Quartz and River Pebbles (Stone Collection)

Mixed assortment containing mainly Silicon Dioxide (SiO2)

Mixed Chalcedony and Jasper Bracelet (possibly 'Ocean Jasper' or similar banded variety for brown beads, and blue/grey Chalcedony for the translucent beads)

Chalcedony (SiO2), Jasper (SiO2 with impurities)

Mixed rock and mineral collection

Mixed lithologies; likely quartz, feldspar, basalt, granite, chert, sandstone, and metamorphic rocks

River Rocks (Polished River Pebbles)

Stream-rounded clastic sediments

Limonitic Gossan

Goethite/Limonite aggregate after sulfide

Mica (specimen appears to be Muscovite or Phlogopite)

Phyllosilicate mineral; Muscovite: KAl2(AlSi3O10)(F,OH)2

Mixed Tumbled Gemstones and River Rocks

Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)

Wishing Rock (Quartz Vein in Host Rock)

Silicon dioxide (SiO2) vein in various host rocks

Calcite (or Alabaster, if truly carved)

Calcium Carbonate (CaCO3)

Pet Rock (Man-made Quartzite or Granite Cobble)

Silicon dioxide (SiO2) mixture; commonly composed of Quartz, Feldspar, and Mica

Magnetite (Lodestone variety)

Magnetite (Fe3O4)

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

Magnetite

Magnetite (Fe3O4)

Magnetite

Magnetite (Fe3O4)

Sapphire

Corundum (Al2O3)

Raw Garnet (Hessonite / Spessartine)

Silicate mineral group (X3Y2(SiO4)3)

Muscovite Mica

KAl2(AlSi3O10)(OH)2

Magnetite Ore

Magnetite (Fe3O4)

Milky Quartz

Silicon Dioxide (SiO2)

Nephrite Jade

Nephrite

Zoisite with Hornblende

Zoisite (Ca2Al3(SiO4)3(OH)) with Amphibole inclusions

Clear Quartz

Silicon Dioxide (SiO2)

Mica

Mica group (often Muscovite or Biotite)

Clear Quartz

SiO2 (Silicon Dioxide)

Greenschist

Greenschist (containing Chlorite, Actinolite, and Epidote)

Apatite

Fluorapatite (Ca5(PO4)3F)

Zoisite with Ruby (Anyolite)

Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)

Pink Quartz

Silicon Dioxide (SiO2)

Quartz with Epidote

Silicon dioxide (SiO2) with Calcium aluminum iron silicate (Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH))

Quartz Heart or Arrowhead Shape

Silicon Dioxide (SiO2)

Magnetite

Iron(II,III) oxide (Fe3O4)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Biotite or Phlogopite Mica

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