The Plumbago North pegmatite, Maine, USA: a new potential lithium resource
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The Plumbago North pegmatite, Maine, USA: a new potential lithium resource William B. Simmons 1
&
Alexander U. Falster 1 & Gary Freeman 2
Received: 23 October 2019 / Accepted: 24 January 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A new spodumene-rich pegmatite was recently discovered on the north side of Plumbago Mountain, Oxford County, Western Maine. The site is about 1.5 km northwest of the famous Dunton gem tourmaline pegmatite. It is an albite-quartz-spodumene pegmatite containing gigantic crystals of spodumene and montebrasite. Some spodumene crystals are more than 11 m in length. The upper portions of the pegmatite contain up to 50 wt% spodumene, which makes it a potentially significant new lithium resource. Preliminary results indicate that Plumbago North Pegmatite contains about 10 Mt of ore with an average Li2O content of 4.68 wt% which is a higher average lithium content than any of the ten top spodumene-producing deposits in the world. Keywords Li-mineralization . Giant crystals . Spodumene . Montebrasite . Plumbago north . Maine
Introduction A new pegmatite was recently discovered on the north side of Plumbago Mountain, Oxford County, Western Maine (Fig. 1). This pegmatite is spodumene-rich and a potentially significant new lithium resource. The site is on the north side of Plumbago Mountain, about 1.5 km northwest of the famous Dunton gem tourmaline pegmatite in an area historically known as Spodumene Brook (Shainin and Dellwig 1955; Barton and Goldsmith 1969). Initial exploration has revealed albite-quartz-spodumene pegmatite containing gigantic crystals of spodumene and montebrasite.
Geology The Plumbago North pegmatite is part of the Oxford pegmatite district, which is situated in the Central Maine Belt (CMB) of Western Maine (Fig. 1). The CMB is a tectonostratigraphic unit Editorial handling: B. Lehmann * William B. Simmons [email protected] 1
2
MP2 Research Group, Maine Mineral and Gem Museum, Bethel, ME 04217, USA Freeman Resources, LLC, 48 Lovejoy Road, South Paris, ME04281, USA
comprised of lower Paleozoic sediments that during assembly of the supercontinent Pangea were deformed and metamorphosed to greenschist to upper amphibolite facies, forming metapelite and metapsammite and an expansive area of migmatite. During the Taconic (Ordovician), Acadian (Late Silurian-Early Devonian), Neoacadian (Late Devonian-Early Mississippian), and Alleghanian (Pennsylvanian-Permian) orogenies, the metamorphic rocks (mainly the migmatites) were intruded by several large granitic bodies (e.g., Sebago and Songo plutons) and numerous smaller ones (Robinson et al. 1998; Bradley et al. 2000). The Plumbago North pegmatite lies within Devonian/Silurian biotite schist (Fig. 1). The Oxford pegmatite district largely coincides with the outer margin of what was formerly mapped as the Sebago Batholith (Osberg et al. 1985; Wise and Brown 2010). As a result of more detailed mapping, the Sebago Batholith was redefined by Solar and Tomascak (2009) as the Sebago Migmatite Domain (
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