Sedimentary (Chemically Precipitated Mineral)

Red Jasper

SiO2 (Microcrystalline Quartz)

Quartz Geode

Silicon Dioxide (SiO2) in Geode form

Chert (with Manganese Dendrites)

Chert (Cryptocrystalline Quartz, SiO2)

Chert (and Flint)

Silicon Dioxide (SiO2)

Ferruginous Sandstone

Arenite with Iron-oxide cement (composed of Quartz and Limonite/Hematite)

Blue-green calcite

Calcite (CaCO₃), likely copper-bearing or otherwise inclusions-colored

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 cement)

Sandstone (Ferruginous)

Arenite (iron-rich)

Chert (River Pebble)

Chert (Cryptocrystalline Quartz, SiO2)

Banded Calcite (often sold as 'Mexican Onyx' or 'Green Onyx')

Calcite (Calcium Carbonate, CaCO3)

Limestone

Calcium carbonate (CaCO3) / Limestone

Yellow calcite

Calcite (CaCO₃), likely honey or amber calcite

Tumbled honey calcite

Calcite (calcium carbonate, CaCO₃)

Raw honey calcite

Calcite (calcium carbonate, CaCO₃)

Hematite-rich ironstone concretion

Hematite (Fe₂O₃), likely mixed with goethite/limonite and silica

Weathered iron-rich mineral concretion

Likely limonite/goethite concretion (hydrated iron oxides), possibly a weathered ironstone fragment

Likely quartz-rich rock fragment

Probably microcrystalline quartz (SiO₂), possibly a pale chert or quartzite fragment

Quartz Pebble

Silicon Dioxide (SiO2)

Banded Chert (Jasper) River Pebble

Microcrystalline Quartz (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Quartz-rich translucent pebble, possibly iron-stained quartz or chalcedony

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)

Weathered iron-rich concretion (probable limonite/goethite)

Limonite–goethite aggregate, approximately FeO(OH)·nH₂O

Likely tumbled white quartz or quartzite pebble

Quartz (SiO₂), possibly quartzite

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Banded Iron Formation (BIF)

Magnetite-hematite-chert formation

Selenite (gypsum)

Gypsum, CaSO₄·2H₂O; fibrous variety often called satin spar

Iron-oxide-rich breccia or weathered ironstone

Hematite–goethite ironstone, likely brecciated and quartz-bearing

Quartz vein specimen

Quartz (SiO₂), likely drusy or massive quartz on host rock

Dolomite on Prehnite (Saddle-shaped Dolomite)

Dolomite [CaMg(CO3)2] on Prehnite [Ca2Al(AlSi3O10)(OH)2]

Iron-rich concretion (probable limonite/goethite concretion)

Hydrated iron oxides, chiefly limonite (FeO(OH)·nH₂O) and goethite (FeO(OH))

Weathered iron-rich rock, possibly limonite-bearing quartzite or altered basalt

Indeterminate; likely quartz (SiO₂) with iron oxides/hydroxides such as limonite/goethite

Orange calcite

Calcite, calcium carbonate (CaCO₃)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Banded iron formation (BIF)

Banded iron formation; chiefly hematite/magnetite and microcrystalline quartz (chert)

Chert (Jasper/Quartzite river pebble)

Microcrystalline Silica (SiO2)

Chert (White Variety)

Silicon Dioxide (SiO2)

Chert (Red Jasper)

Microcrystalline Quartz (SiO2)

Calcite crystal specimen

Calcite — calcium carbonate, CaCO₃

Banded iron formation (iron-rich jasper/chert)

Banded iron formation, composed mainly of hematite–magnetite with microcrystalline quartz (jasper/chert)

Honey calcite cluster

Calcite (calcium carbonate, CaCO₃)

Banded Chert / Flint

Silicon dioxide (SiO2)

Banded iron formation fragment (likely hematite–magnetite ironstone)

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