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Igneous veins are generally formed through hydrothermal (hot water) action. They can occur in any type of igneous rock, although specific ores only appear in specific rock types. Note that this page excludes special types of igneous veins, like serpentine and pegmatite.

Ore Rock Notes
Cassiterite Granite 5% gold, 5% scheelite
Chalcopyrite Granite 10% gold
Chromite Diorite 2x ocean, volcanic
Cinnabar Basalt Only ocean
Magnetite Granite
Stibnite Granite
Alunite Andesite, rhyolite
Perlite Peridotite, diorite, gabbro Only volcanic
Quartz Granite
Realgar Granite Continental

Granite veins are 25% more frequent in volcanic regions.