Potential for critical mineral deposits in Maine, USA

Abstract

An analysis of the potential for deposits of critical minerals and elements in Maine presented here includes data and discussions for antimony, beryllium, cesium, chromium, cobalt, graphite, lithium, manganese, niobium, platinum group elements, rhenium, rare earth elements, tin, tantalum, tellurium, titanium, uranium, vanadium, tungsten, and zirconium. Deposits are divided into two groups based on geological settings and common ore-deposit terminology. One group consists of known deposits (sediment-hosted manganese, volcanogenic massive sulphide, porphyry copper-molybdenum, mafic- and ultramafic-hosted nickel-copper [-cobalt-platinum group elements], pegmatitic lithium-cesium-tantalum) that are in most cases relatively large, well-documented, and have been explored extensively in the past. The second, and much larger group of different minerals and elements, comprises small deposits, prospects, and occurrences that are minimally explored or unexplored. The qualitative assessment used in this study relies on three key criteria: (1) the presence of known deposits, prospects, or mineral occurrences; (2) favourable geologic settings for having certain deposit types based on current ore deposit models; and (3) geochemical anomalies in rocks or stream sediments, including panned concentrates. Among 20 different deposit types considered herein, a high resource potential is assigned only to three: (1) sediment-hosted manganese, (2) mafic- and ultramafic-hosted nickel-copper(-cobalt-platinum group elements), and (3) pegmatitic lithium-cesium-tantalum. Moderate potential is assigned to 11 other deposit types, including: (1) porphyry copper-molybdenum (-rhenium, selenium, tellurium, bismuth, platinum group elements); (2) chromium in ophiolites; (3) platinum group elements in ophiolitic ultramafic rocks; (4) granite-hosted uranium-thorium; (5) tin in granitic plutons and veins; (6) niobium, tantalum, and rare earth elements in alkaline intrusions; (7) tungsten and bismuth in polymetallic veins; (8) vanadium in black shales; (9) antimony in orogenic veins and replacements; (10) tellurium in epithermal deposits; and (11) uranium in peat.

A Recently Discovered Trachyte-Hosted Rare Earth Element-Niobium-Zirconium Occurrence in Northern Maine, Usa

“…1). This region was selected because of the presence of the large, 30-Mt Ordovician Bald Mountain Cu-Zn-Ag-Au(-Co-Sb-Se-Te-Bi) volcanogenic massive sulfide (VMS) deposit (Slack et al, 2003) and large stratiform Mn deposits hosted in Silurian sedimentary rocks northeast of the volcanic terrane (total 327 Mt @ 9.0 wt % Mn; Pavlides, 1962;Slack et al, 2022), and the potential for additional VMS and other deposit types that might contain critical metals. The new airborne radiometric data (gamma-ray spectrometry for K, eU, and eTh) generally show low values of eTh except for an anomaly on the eastern side of Pennington Mountain (Fig.…”

“…Maine has a diverse metallogeny that includes a high potential for undiscovered major critical mineral deposits of stratiform manganese in sedimentary rocks, nickel-copper(-cobalt-PGEs) in mafic and ultramafic intrusions, and lithium in granitic pegmatites (Slack et al, 2022). Prior to this discovery at Pennington Mountain, no potentially economic concentrations of REE, Nb, or Zr were known in Maine (Mariano and Mariano, 2012;Van Gosen et al, 2017, 2019.…”