Mission Mine Project
Deposit Formation
The source of the heavy minerals (HM) is believed to be derived predominately from erosion of the Trail Ridge to the west. Additional longshore transportation of heavy mineral bearing sands were derived from drainages in southern Georgia which transported sand containing valuable heavy minerals originating from high grade metamorphic and igneous source rocks of the southern Appalachian Mountains (Minerals Derived From Mountain Sources). This is also believed to be the primary source of the Trail Ridge deposits in Florida and Georgia.
The deposits are a series of ancient barrier island (Mineral Upgrading on Beaches) sequences deposited during interglacial periods of Pleistocene time and are believed to be between 1 to 2 million years old. An initial transgression of the ocean up to the western extents of the Mission orebody occurred during an extensive sea-level stillstand. This period was followed by sporadic transgressive and regressive cycles where the sea level came up and went back repeatedly over thousands of years.
The deposit assemblage is composed of predominately ilmenite with moderate amounts of zircon, rutile, and leucoxene. The assemblage across the orebody is highly variable. The variability can result in the HM concentrate value to change by greater than 50%. The range of ilmenite plus leucoxene percentages can change from 25% to 45%, rutile product percentages can range from 9% to 20%, and zircon percentages can vary from 9% to 24%.
The deposit has 5 to 25% humate undersize. The deposit is predominately loose uncemented fine-grained sand with occasional humate hardpan. The mineralized zones are not readily distinguishable from the unmineralized sands below.
Five economic heavy mineral deposits are known along this ancient beach ridge stretching through Florida and Georgia. These are (from south to north) the Green Cove Springs Mine, Boulogne Mine, Folkston Mine, Mission, and Lulaton. The Green Cove Springs, Boulogne and Folkston deposits have been mined using dredge operations by Iluka (GCS Mine since the 1970's) and Humphreys Mining (Boulogne, Folkston 1970's). The Lulaton area was mined during the mid-2000's by TE Consolidated (an Iluka subsidiary).
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