Organic Gemstone (Often Associated With Sedimentary Sequences)

Jasper

Jasper (SiO2)

Yellow Chert (Chert / Cryptocrystalline Quartz)

Silicon Dioxide (SiO2)

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Jasper/Chalcedony pebble)

Microcrystalline Quartz (SiO2)

Chert (Jasper variation)

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amber

Succinite (approximate formula C10H16O)

Chert (Jasper)

Silicon Dioxide (SiO2)

Rhodonite

Rhodonite (Manganese Iron Magnesium Calcium Silicate - (Mn,Fe,Mg,Ca)SiO3)

Chert (Cherty Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Iron-rich concretion or weathered ironstone pebble

Goethite/limonite-bearing ironstone; commonly an iron-oxide concretion (FeO(OH)·nH₂O, variable)

Banded chert or silicified limestone nodule

Microcrystalline quartz (SiO₂), possibly replacing carbonate fossils

Jasper (Iron-stained Quartzite/Chert)

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) impurities

Likely galena-bearing metamorphic sulfide ore

Galena (PbS), possibly with pyrite and/or sphalerite in a schistose host

Chert (variations like Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

White quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly micaceous or feldspathic

Chert (Light Grey / Flint variant)

Cryptocrystalline Quartz (SiO2)

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Blue Chalcedony

Chalcedony (a cryptocrystalline variety of Quartz - SiO₂)

Calcite-rich limestone, possibly fossiliferous

Limestone composed mainly of calcite (CaCO₃), potentially containing a fragmentary fossil or calcite-filled structure

Banded chert or siliceous mudstone

Microcrystalline quartz (chalcedony), SiO₂; possibly ferruginous shale

Chert (Cherty Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Red Jasper (Chert)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Green Chert

Microcrystalline Quartz (SiO2)

Jasper

Silicon dioxide (SiO2) with impurities

Chert (specifically Flint or Jasper variant)

Silicon Dioxide (SiO2)

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Lapis Lazuli

Rock composed mainly of lazurite ((Na,Ca)8(AlSiO4)6(SO4,S,Cl)2), calcite, and pyrite

Chert (Jasper / Petrified Wood)

Microcrystalline Quartz (SiO2)

Chert (Iron-stained or Dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Garnet Schist

Garnetiferous Micaceous Schist

Chert (Flint)

Silicon Dioxide (SiO2)

Amazonite

Microcline (KAlSi3O8) with lead impurities

Chalcedony (Agate/Carnelian)

Cryptocrystalline Quartz (SiO2)

Bloodstone

Chalcedony (Quartz)

Jasper

Jasper (Silicon Dioxide, SiO2)

Chert / Chalcedony

Silicon Dioxide (SiO2)

Chert (Yellow Jasper variant)

Silicon Dioxide (SiO2)

Chert (Flint)

Chert (Microcrystalline Quartz, SiO2)

Chert (Jasper/Chalcedony)

Microcrystalline Silica (SiO2)