In November 2023, Avalon Advanced Materials Inc. and Sibelco Group established a joint venture for Avalon’s lithium projects, including the Separation Rapids and Lilypad projects in northwestern Ontario. The partnership involved the creation of a joint venture company called Separation Rapids Ltd., with ownership divided between Sibelco, holding a 60% stake, and Avalon, owning the remaining 40%.
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Summary:
The Separation Rapids Lithium Deposit (SRLD) is underlain predominantly by a mafic metavolcanic sequence, consisting of flows, tuffs, subordinate epiclastic metasediments and rare iron formation horizons and rhyolites.
The drill tested portion is about 750 m in strike length, of which about 300 m is considerably thicker and thus contains the bulk of the presently defined mineral resource. The further continuation of the pegmatite 450 m to the west is thinner and has a few shallow drill holes. This thin portion, drilled in the past, has been informally referred to as Bob’s Pegmatite.
There is yet further extension of the thinner pegmatite in sparse outcrops to the west for approximately 400 m, referred to normally as the “Western Pegmatite”.
The thickest part of the SRLD, historically referred to as the Big Whopper Pegmatite, forms a large lens-shaped body approximately 400 m long and approximately 70 m at its widest part.
The SRLD narrows to less than 20 m at both its eastern and western ends, and extends along strike in both directions for at least 300 m in the form of relatively narrow tails up to 10 to 15 m wide. Smaller, subparallel, 1 m to 10 m wide, petalite-bearing pegmatite bodies predominantly occur to the northeast, north and northwest of the main SRLD body, with minor occurrences on the southern flank.
The narrower west-southwest-striking zone of petalite pegmatites extends from the main SRLD for a distance of approximately 750 m to the west and is exposed in four outcrops, namely the Great White North, Bob’s, Swamp and West pegmatites.
Avalon has further subdivided the SRLD into three sub-zones, namely the Separation Rapids Pegmatite, Western Pegmatite and Eastern Swarm. Based on lithological, mineralogical and textural variations, the Separation Rapids Pegmatite itself has been subdivided into five distinct lithological units and subunits, 3a, 3b, 4, 5 and 6, that outcrop as irregular dykes and larger irregular to elliptical bodies intruding the amphibolite and granites.
The main SRLD is flanked by a swarm of narrower petalite-bearing, highly feldspathic pegmatites, albitite and albite-potassium feldspar zones, subunits, 3a and 3b. These two subunits make up a significant portion of the northwestern part of the SRLD. Subunit 3a occurs as discrete, strongly foliated aplitic zones proximal to the SRLD and internally as endocontact border zones proximal to the amphibolite. Subunit 3b occurs as medium-grained, potassium feldspar-rich megacrystic dykes, which are somewhat similar to the Subunit 3a dykes and also occur within the same portions of the northwestern SRLD.
The potassium feldspar-rich zone lithology that constitutes Unit 4 is confined, on surface, to the northwestern and southwestern peripheral zones and two narrow, 20 m to 30 m long zones on the southern margin of the main zone.
Unit 5 occurs as irregular zones commonly associated and interbanded with Unit 4 in the northern and northwestern zone peripheral to the main SRLD. The Unit 5 zones tend to be less than 20 m in length (except for one larger, 60- m long zone on the northwestern flank). At depth, Unit 5 is intersected in drill core, on sections 250 W, 300 W and in sections 450 W 500 W and 550 W in the “Flame Structure”. In total, Unit 5 constitutes 17% of the feldspathic units in the SRLD.
Within the intermediate zone of the Separation Rapids Pegmatite the predominant lithology is the petalite-bearing Unit 6. Avalon has subdivided this unit into four textural and compositional subunits: 6a, 6b and 6c form the bulk of the petalite pegmatite.
Discontinuous albitic dykes, commonly with petalite cores, occur in boudinaged, pinch- and swell swarms proximal to the northern contact of the SRLD and the Western Pegmatite. Most are narrow and less than 1 m wide, with exceptions reaching 12 to 15 m in width and 150 m in length, including a lepidolite-rich dyke encountered in diamond drilling, and referred to as the Lepidolite Dyke.
Pegmatitic granite dykes and larger elliptical intrusions related to the Separation Rapids Pluton outcrop at several locations on the property. These rocks (Unit 7) consist predominantly of white rubidium-rich potassium feldspar, with subordinate amounts of albite, green lithian muscovite, quartz, accessory garnet (spessartine), cassiterite, apatite, tantalum oxides and granite.
Geological mapping and diamond drilling show that the SRLD system has a strike length of over 1.5 km, and widths ranging from 10 to 70 m. To date, the SRLD has been intersected by drilling to a vertical depth of almost 275 m. The petalite-bearing pegmatite zones show little variation in true width between surface outcrop, up to 70 m, and up to 45 m for near-surface and the deepest intersected levels. These petalite zones are open to depth.
The central portion of the SRLD is a low, dome-shaped hill, formed by the well-exposed main mineralized zone. It has a strike length of 600 m with a drill-tested vertical depth of at least 250 m. It forms the widest portion of the SRLD, averaging 55 m over a 300 m strike length.
Surface geological mapping and diamond drilling carried out by Avalon between lines 550W and 700W show that the Western Pegmatite is the western continuation of the Separation Rapids Pegmatite, with the width narrowing significantly to 10 m and less.