Sedimentary (Secondary Mineral) Within Igneous

Pink Feldspar

Potassium Feldspar (Microcline or Orthoclase), KAlSi3O8

Gneiss

Gneiss (Metamorphic Rock)

Limonite with Galena

FeO(OH)·nH2O (Limonite) and PbS (Galena)

Chrysocolla

Hydrated copper phyllosilicate, (Cu,Al)2H2Si2O5(OH)4·nH2O

Gneiss (with Garnet)

Gneiss (Feldspar-Quartz-Biotite-Garnet Metamorphic Rock)

Gneiss (Metamorphosed Granitic Rock)

Gneiss (composed mainly of quartz, feldspar, biotite, and/or hornblende)

Quartz geode or quartz-bearing rock

Quartz (SiO₂), likely in a chalcedony- or basalt-hosted cavity

Quartz Pebble (Geode Nodules / Stream-Rounded Quartz)

Silicon Dioxide (SiO2)

Granitic Gneiss

Gneiss (Metamorphic rock predominantly containing quartz, K-feldspar, and plagioclase)

Vesicular basalt (possibly slag-contaminated)

Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals

Gneiss

Gneiss (Foliated Metamorphic Rock)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Gneiss (Hornblende/Biotite Gneiss)

Foliated Metamorphic Rock (Quartz-Feldspar-Amphibole/Mica matrix)

Limonite with Quartz

Hydrated Iron Oxide Hydroxide with Silicon Dioxide (FeO(OH)·nH2O + SiO2)

Quartz (Iron-stained or Milky)

Silicon Dioxide (SiO2)

Quartz (Smoky/Milky variety)

Silicon Dioxide (SiO2)

Limonite (Ironstone)

Goethite/Limonite (Hydrated iron(III) oxide-hydroxide)

Chert (specifically Jasper or Brown Chert node)

Microcrystalline Quartz (SiO2)

Porphyritic basalt (vesicular basalt)

Basalt; fine-grained mafic rock, commonly composed of plagioclase, clinopyroxene, olivine, and iron-titanium oxides

Rose Quartz

Rose Quartz (SiO2)

Botryoidal Agate / Chalcedony Geode

Silicon Dioxide (SiO2)

Quartz in Matrix

Silicon Dioxide (SiO2)

Basalt with Amygdules

Extrusive Igneous Rock (Mafic)

Quartz with Iron Oxide Stain

Silicon Dioxide (SiO2) with Hematite/Limonite coatings

Chert (Banded Variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock; likely containing plagioclase and pyroxene with weathering products

Pebble with vesicles, likely basalt

Vesicular basalt; chiefly plagioclase, pyroxene, and iron-magnesium minerals

Chert (specifically a stream-worn Chert Nodule)

Sedimentary Cryptocrystalline Quartz (SiO2)

Ferruginous Quartz

Iron-stained Quartz (SiO2 with Fe2O3 impurities)

Quartz Geode

Crystalline Quartz (SiO2) within a sedimentary/igneous host

Yellow Ochre / Limonite

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Limonite or Goethite (Ironstone)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Kaolinite (China Clay)

Kaolinite (Al2Si2O5(OH)4)

Limonite

FeO(OH)•nH2O

Basalt with Amygdules

Amygdaloidal Basalt

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Banded Agate (Agatized Geode Slice)

Silicon Dioxide (SiO₂)

Clear Quartz (Druzy)

Crystalline Silicon Dioxide (SiO2)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Milky Quartz with Iron Oxides

Silicon Dioxide (SiO2) with Fe2O3 inclusions

Agate Geode

Chalcedony (SiO2 - Silicon Dioxide)

Blue-dyed Quartz Druzy

Silicon Dioxide (SiO2) with artificial pigment