An ore mineral that was deposited during the original period or periods of metallization. The term has also been used to designate the earliest of a sequence of ore minerals, as 2459 contrasted with later minerals of the same sequence, which some writers have called secondary. To avoid confusion, Ransome proposed the terms hypogene and supergene. Hypogene, as the word implies, indicates formation by ascending solutions. All hypogene minerals are necessarily primary, but not all primary ore minerals are hypogene; e.g., sedimentary hematite is of primary deposition even though it formed as a low-temperature precipitate.