Ore genesis accumulation of hematite gravels called "pisolites" which form channel-iron deposits. These are preferred because they are cheap to mine. Lead-zinc deposits are generally accompanied by silver, hosted within the lead sulfide mineral galena or within the zinc sulfide mineral sphalerite. Lead and zinc deposits are formed by discharge of deep sedimentary brine onto the sea floor (termed "sedimentary exhalative" or SEDEX), or by replacement of limestone, in skarn deposits, some associated with submarine volcanoes (called volcanogenic massive sulfide ore deposits or VMS), or in the aureole of subvolcanic intrusions of granite. The vast majority of SEDEX lead and zinc deposits
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