Ore genesis and loses its metal carrying capacity. Ore deposits rarely fit neatly into the categories in which geologists wish to place them. Many may be formed by one or more of the basic genesis processes above, creating ambiguous classifications and much argument and conjecture. Often ore deposits are classified after examples of their type, for instance Broken Hill type lead-zinc-silver deposits or Carlin–type gold deposits. Classification of hydrothermal ore deposits is also achieved by classifying according to the temperature of formation, which roughly also correlates with particular mineralising fluids, mineral associations and structural styles. This scheme, proposed by Waldemar Lindgren (1933)
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