Galena Sardinia. In the United States, it occurs most notably in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri, and in the Driftless Area of Illinois, Iowa and Wisconsin. Galena also was a major mineral of the zinc-lead mines of the tri-state district around Joplin in southwestern Missouri and the adjoining areas of Kansas and Oklahoma. Galena is also an important ore mineral in the silver mining regions of Colorado, Idaho, Utah and Montana. Of the latter, the Coeur d'Alene district of northern Idaho was most prominent. Galena is the official state mineral of the U.S. states
Primary minerals as basalt, rhyolite, andesite and obsidian) and intrusive rocks (such as granite, granodiorite, gabbro and peridotite) contain primary minerals including quartz, feldspar, plagioclase, muscovite, biotite, amphibole, pyroxene and olivine in varying concentrations. For the classical discussions of the origin of primary ores, see the two publications "Ore Deposits" (1903 and 1913). According to W.A. Tarr (1938) the primary mineral deposits are the result of direct magmatic action; he states that the splitting of magmas results in the basic igneous rocks and their accompanying group of accessory minerals formed by the first crystallization in the magma, on the one hand, and