Sedimentary (Chemically Precipitated Mineral)

Jasper

Microcrystalline Quartz (SiO2) with iron oxide impurities

Jasper

Microcrystalline quartz (SiO2)

Limonite (Limonitic Sandstone)

Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)

Pyrite-bearing rock (likely pyrite-rich schist or quartz-bearing sulfide ore)

Pyrite (FeS₂) in a rock matrix; exact host rock cannot be confirmed from the photo

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz pebble

Silicon dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Banded iron formation (ironstone), possibly hematite–magnetite-rich

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and chert/microcrystalline quartz (SiO₂)

Banded iron formation fragment (likely hematite–magnetite-rich ironstone)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica/chert (SiO₂)

Likely brown ironstone or limonite-rich rock fragment

Ironstone, chiefly iron oxides/hydroxides such as goethite (α-FeO(OH)) and limonite

Jasper with Quartz inclusion

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Tumbled dark stone, likely banded iron formation or hematite-rich jasper

Hematite-bearing quartz/jasper; probable iron oxide–silica aggregate

Jasper

Silicon Dioxide (SiO2), Microcrystalline Quartz

Green Jasper / Chert Pebbles

Microcrystalline Quartz (SiO2)

Moqui Marble (Shaman Stone)

Ironstone Concretion (Goethite/Hematite-cemented Sandstone)

Agate Geode

Silicon dioxide (SiO2)

Likely iron-rich metamorphic rock (possibly hematite-rich ironstone)

Uncertain from the image; possible hematite-bearing ironstone, chiefly Fe₂O₃ with associated silicate minerals

Iron-rich jasper or ferruginous chert

Microcrystalline quartz (SiO₂) stained by iron oxides, chiefly hematite and goethite

Banded chert pebble

Chert (microcrystalline quartz, SiO₂), likely ribbon-banded chert

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Dendritic Opal

Hydrated amorphous silica with manganese oxide inclusions (SiO2·nH2O)

Quartz

Silicon Dioxide (SiO2)

Quartz

Quartz (Silicon Dioxide, SiO2)

Geode

Quartz nodule

Amethyst Geode Fragment

Quartz (SiO2) with trace iron impurities

Orange Calcite with Siderite/Iron Oxide Coating

Calcium Carbonate (CaCO3)

Quartz

Silicon Dioxide (SiO2)

Quartz / Calcite Pebble (Indeterminate due to severe blur)

SiO2 (Quartz) or CaCO3 (Calcite)

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Banded Calcite (Onyx Marble)

Calcite (CaCO3) / Travertine

Jasper

Silicon dioxide (SiO2) with iron impurities

Milky quartz crystal cluster

Quartz, silicon dioxide (SiO₂)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz-rich mineral fragment

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Orange chert (likely jasper)

Microcrystalline quartz (SiO₂), iron-oxide stained; jasper is an opaque variety of chert

Quartz

SiO2 (Silicon Dioxide)

Pyrite in Quartz Matrix

Iron Sulfide (FeS2) embedded in Silicon Dioxide (SiO2)

Dyed Blue Agate Slice

Chalcedony (Silicon Dioxide, SiO2)

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrous iron oxides)

Wishing Stone (Basalt or Siltstone with Quartz/Calcite Vein)

Basalt (SiO2+MgO+FeO) or Siltstone with a Quartz (SiO2) or Calcite (CaCO3) vein

Likely chert/flint fragment

Microcrystalline quartz (SiO₂), possibly partially weathered chert