Carbonate-hosted lead-zinc ore deposits and pyrite thus form. Commonly MVT deposits form by the combination of hydrocarbon pyrolysis liberating zinc-lead ions and sulfur to form an acidic solution which dissolves the host carbonate formation and replaces it with massive sulfide accumulations. This may also take the morphology of fault-hosted stockworks, massive tabular replacements and so forth. Porous limestones may form disseminated ores, however most MVT deposits are massive sulfides with knife-like margins between carbonate and sulfide mineralogies. Ore minerals in carbonate replacement deposits are typically lead sulfide, galena, and zinc sulfide sphalerite. Weathered equivalents form anglesite, cerussite, smithsonite, hydrozincite and secondary galena and sphalerite
Galena, Alaska upon the closure of Galena Air Force Station. As Galena is incorporated as a first-class city and located in the Unorganized Borough, it is required by state law to operate its own schools, Galena City School District, apart from the Rural Education Attendance Areas which otherwise prevail outside of incorporated boroughs. Along with other such cities across Alaska, Galena's school district operates a boarding school and a correspondence study program, to increase state funding which would not otherwise be available with the local pupil base. Galena has three schools. Galena City School is primarily for local K–12 students. There is