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Geologic units containing skarn

Arizona

Early Tertiary to Late Cretaceous granitic rocks (Late Cretaceous to Early Tertiary)

Porphyritic to equigranular granite to diorite emplaced during the Laramide orogeny. Larger plutons are characteristically medium-grained, biotite +/- hornblende granodiorite to granite. Smaller, shallow-level intrusions are typically porphyritic. Most of the large copper deposits in Arizona are associated with porphyritic granitic rocks of this unit, and are thus named 'porphyry copper deposits'. (50-82 Ma)

Jurassic to Cambrian metamorphosed sedimentary rocks (Cambrian to Jurassic)

Highly faulted and folded rocks of units Jv, J_, and Pz, deformed and metamorphosed in Jurassic, Cretaceous and Tertiary time. This unit is restricted to west-central Arizona. (160-540 Ma)

Idaho

Limestone, slate; Upper Triassic greenschist-facies metamorphic rocks; western Idaho, Blue Mountains island-arc complex; (Late Triassic)

Upper Triassic shale overlying reefal limestone and dolomite in west-central Idaho.

Quartzite and biotite schist in fault contact; Middle Proterozoic metasedimentary rocks; southern Belt province (Middle Proterozoic)

Intermediate Precambrian age metasediments; dominantly quartzite with minor micaceous layers and mica schists of northern Idaho

Schist, quartzite, marble, skarn, and mafic gneiss; Jurassic to Mississippian amphibolite-facies rocks; southwestern Idaho, western accreted island-arc complex (Jurassic to Mississippian)

Metamorphic complex of probable Paleozoic units of southwestern Idaho.