Mineral (Silicate Replaced Organic Material)

Scoria (Volcanic Rock)

Scoria (often basaltic scoria)

Black Marble with Quartz Veining

Metamorphosed Limestone (Recrystallized CaCO3)

Agate

Agate (Silicon Dioxide, SiO2)

Quartz (Milky/Yellowish variety)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon dioxide (SiO2)

Fluorite

Calcium Fluoride (CaF2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Labradorite

Labradorite (Plagioclase Feldspar Series: (Ca,Na)(Al,Si)4O8)

Sandstone

Arenite

Banded Gneiss

Gneiss (High-grade Metamorphic Rock)

Sandstone

Arenite (Sedimentary rock composed of sand-sized grains, primarily SiO2)

Sandstone (Micaceous/Feldspathic variant)

Arenite (specifically subarkose or lithic arenite)

Sandstone (with Liesegang rings or Oxidation)

Arenite (primarily Quartz SiO2 with Iron Oxide Fe2O3 staining)

Sandstone

Clastic Sedimentary Rock (composed mostly of SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (Fossiliferous)

Clastic Sedimentary Rock (primarily SiO2)

Pink Opal / Peruvian Opal

Hydrated amorphous silicon dioxide (SiO2·nH2O)

Amazonite (likely mixed with other feldspars/minerals)

Amazonite is a variety of Microcline, which is a tectosilicate mineral, formula KAISi3O8. The mixed beads could include other feldspars or quartz.

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide staining/cementing)

Malachite in Matrix

Copper Carbonate Hydroxide (Cu2CO3(OH)2)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Diamond (set in a gold ring)

Carbon (C) - Adamantine cubic carbon

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (Quartz Arenite)

Sandstone (Chemical formula: primarily SiO2)

River Stone (Quartzite/Siltstone mixture)

Silicon Dioxide (SiO2) based metamorphosed sandstone

Quartz (Milky or Druzy Quartz)

Silicon Dioxide (SiO2)

Quartz (Milky/Smoky variety)

Silicon Dioxide (SiO2)

Olivine (Peridot)

Olivine Group (Mg,Fe)2SiO4

Labradorite (Polished Crystal Point)

Labradorite (a calcium-enriched feldspar mineral), (Ca, Na)(Al, Si)4O8

Graphite

Graphite (Chemical Formula: C)

Sandstone

Arenite (primarily SiO2)

Red Jasper

Jasper (Silicon Dioxide with Iron Oxide inclusions - SiO2)

Dyed Agate

Silicon Dioxide (SiO2) - variety Chalcedony

Slag

Metallurgical by-product

Sandstone

Clastic sedimentary rock (primarily SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (likely Quartzose Sandstone)

Arenite (primarily SiO2)

Sandstone (Greywacke/Siltstone variant)

Clastic Sedimentary Rock (composed primarily of Quartz SiO2 and Feldspar)

Sandstone (Ferruginous)

Arenite (Fe-rich SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)