Metamorphic Or Igneous Alteration

Clear Quartz

SiO2 (Silicon Dioxide)

Yellow Sapphire or Citrine

Al2O3 (Corundum) or SiO2 (Quartz)

Weathered basalt (possibly vesicular basalt)

Basalt; chiefly plagioclase, pyroxene, and iron-titanium oxides

Weathered volcanic rock, likely andesite or basalt

Fine-grained mafic to intermediate volcanic rock; commonly plagioclase, pyroxene, and possible iron oxides

Vesicular basalt (possibly amygdaloidal basalt)

Basalt, chiefly plagioclase feldspar and pyroxene, with possible olivine and secondary mineral infillings

Green Andesite (or Greenstone / Altered Volcanic Rock)

Intermediate Volcanic Rock with Chlorite/Epidote Alteration

Weathered iron-rich basalt or volcanic rock

Fine-grained mafic rock, likely basalt with iron-oxide weathering (hematite/goethite)

Weathered volcanic rock, likely andesite or basaltic-andesite

Fine-grained plagioclase–pyroxene volcanic rock; possible altered andesite (exact identification requires testing)

Tumbled dark green mafic rock, likely basalt or diabase

Fine-grained basalt/diabase; chiefly plagioclase feldspar and pyroxene, with possible olivine and magnetite

Weathered purple rhyolite (probable porphyritic volcanic rock)

Rhyolite, commonly quartz–alkali-feldspar–plagioclase with minor biotite or iron oxides

Banded basalt pebble with a quartz-rich vein

Basalt, likely amygdaloidal or hydrothermally altered; chiefly plagioclase feldspar and pyroxene, with quartz/calcite and iron oxides

Rounded river cobble, likely basaltic rock

Fine-grained mafic volcanic rock, probably basalt or altered basalt

Dark river pebble, likely basalt or fine-grained volcanic rock

Basalt (probable); mostly plagioclase and pyroxene, with possible magnetite

Red granite or granitic gneiss pebble

Felsic granitoid, likely quartz–feldspar–biotite granite; possible weakly gneissic texture

Rhyolite or jasper-bearing volcanic rock

Rhyolite, likely altered and silicified; red coloration may come from hematite

Rhyolitic jasper / brecciated jasper

Silica-rich volcanic rock, chiefly microcrystalline quartz (SiO₂), with iron-oxide and clay/mineral impurities

Zoisite with Ruby (Anyolite)

Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)

Biotite on Quartz

Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2) and Quartz (SiO2)

Quartz (Pebble)

Silicon Dioxide (SiO2)

Likely basaltic rock

Basalt, a fine-grained mafic volcanic rock composed chiefly of plagioclase feldspar, pyroxene, and commonly olivine

Quartz with Epidote

Silicon dioxide (SiO2) with Calcium aluminum iron silicate (Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH))

Pink Quartz

Silicon Dioxide (SiO2)

Polished zebra jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and manganese-rich banding

Weathered gray rock, likely basaltic or andesitic fragment

Fine-grained mafic to intermediate volcanic rock; exact identification requires fresh surface and testing

Blue Apatite

Apatite, Ca5(PO4)3(F,Cl,OH)

Vesicular basalt (likely weathered volcanic rock)

Basalt; primarily plagioclase feldspar, pyroxene, and possible olivine

Weathered basaltic volcanic rock

Likely vesicular basalt or basaltic-andesite; chiefly plagioclase, pyroxene, and iron-bearing minerals

Likely weathered basalt or mafic volcanic rock

Basalt; chiefly plagioclase feldspar, pyroxene, and possibly olivine

Weathered quartz-rich pebble

Likely altered granite or granitic gneiss; chiefly quartz and feldspar with minor mica/iron oxides

Quartz (Rock Crystal) with minor impurities

Quartz (SiO2)

Quartz Heart or Arrowhead Shape

Silicon Dioxide (SiO2)

Hematite

Hematite (Fe2O3)

Basalt with Epidote/Chlorite

Amygdaloidal Basalt (SiO2 with (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)))

Feldspar (Plagioclase / Potassium Feldspar)

Feldspar Group (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)

Pink Granite

Phaneritic Felsic Igneous Rock (high K-feldspar)

Magnetite

Iron(II,III) oxide (Fe3O4)

Magnetic Hematite

Magnetized Hematite (an iron oxide mineral, Fe2O3, that has undergone magnetization)

Vesicular basalt

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar, pyroxene, and often olivine

Weathered feldspathic rock, likely granite or granitic pegmatite

Quartz–feldspar–mica aggregate; exact species indeterminate from the image

Porphyritic basaltic-andesite

Porphyritic intermediate volcanic rock; chiefly plagioclase and pyroxene/amphibole, with altered mafic minerals and iron oxides

Serpentinite (Serpentine Rock)

Primarily composed of serpentine group minerals, such as antigorite, chrysotile, and lizardite. Chemical formula for serpentine minerals is (Mg,Fe)3Si2O5(OH)4.

Serpentine, likely a variety of Chrysoprase (green chalcedony) or a similar translucent green mineral.

Serpentine Group Minerals (e.g., Antigorite, Lizardite) or Chalcedony (SiO2) with nickel impurities for Chrysoprase green.