Pine Point Mining Limited (“PPML”) is a joint venture formed between Osisko Metals Incorporated (“Osisko”) and a fund advised by Appian Capital Advisory LLP (“Appian”) entered into on April 6, 2023, and amended on February 22, 2024, where Appian can earn up to a 65% interest in PPML. As of May 15, 2024, the ownership in the Joint venture is Osisko (54%) and Appian (46%). The joint venture controls a 100% interest in the Pine Point property.
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Summary:
The Pine Point deposits are carbonate-hosted lead-zinc sulphide deposits with aspects of Mississippi Valley-Type (“MVT”) and a broader class of deposits called “sediment-hosted Pb-Zn” deposits (Leach et al., 2010). Mineralization is hosted in three distinct deposit types:
1. Prismatic-type Deposits - Prismatic deposits demonstrate considerable vertical continuity but with limited lateral extent and are discordant. Mineralization is coarse to medium grained. These deposit types are further divided into normal and abnormal prismatic deposits based on their relative stratigraphic position in the sequence. They contributed greatly to the Pine Point historical production as they contained very high-grade base metal grades and thicknesses.
Prismatic deposits are generally high-grade and can contain up to 50% combined Pb-Zn, depending on the amount of sulphide mineralization present. These deposits are vertically continuous for up to 60m, and laterally restricted, generally 15-50m, but can be up to 140m wide. Metal zonation is present with a galena-rich core (Pb/Pb+Zn >0.3) enveloped by a more sphalerite-rich outer zone.
Prismatic deposits generally initiate at the Pine Point/Sulphur Point Formation facies transition and extend upwards through a dolomitized stratigraphic section, including upper sequences such as the Slave Point Formation. Abnormal prismatic deposits generally initiate within the lower stratigraphic sequences and extend upward.
These types of deposit generally contain blocks of overlying and adjacent stratigraphic material. Such blocks can exhibit angular and dissolution textures. Cavities and vugs are common and abundant internal sediment accumulations are observed to fill earlier open spaces. These sediments are the residues of intense hydrothermal dissolution consisting of insoluble carbonaceous debris, argillite components, and sulphide material. It is believed that these sediments are remnants of the intense hydrothermal dissolution process associated with sulphide emplacement.
2. Tabular-type Deposits - Laterally continuous, semi-concordant mineralized zones, mostly restricted to a specific carbonate horizon. Two types are now recognized:
a) Normal tabular deposits are developed in the Sulphur Point Formation and the topmost portion of the Pine Point Formation. These are associated with intense HYD alteration;
b) Abnormal stratabound deposits occur in the interpreted middle of the Pine Point Formation. They occur with sparse hydrothermal alteration.
Tabular-type deposits are correlatable, stratabound mineralization extending over a significant strike length at varying lateral widths from 50 to 200 metres wide. The strike extent can be in the order of kilometres. Mineralization thickness averages about 3 metres and can range from 1 m to, very locally, greater than 10 m. Using composite grades, a clearly defined keel of higher-grade mineralization can be mapped in most Tabular-type deposits. Lead and zinc sulphides are present in the Tabular keel mineralization, whereas the distal portions are dominated by zinc sulphide. Multiple stacked levels of Tabular mineralization are common. Tabular-type deposits are developed in the Sulphur Point Formation in the Main Trend and within the top of the Pine Point Formation in the North Trend. In both cases, HTD alteration is characteristic.
These Tabular deposits have an affinity for distinct biomicrite facies carbonate sequences and, according to recent interpretation, follow structural corridors exhibiting low-offset horst and graben features. They are laterally continuous, following the general carbonate reef trend as well as the structural trend.
Tabular deposits are lower-grade, relative to Prismatic deposits, due to less massive and sporadic sulphide development. Zinc and lead grades decrease outwards from the core of hydrothermal fluid pathways (channels) and distally from interpreted local ‘feeder’ structures. Tabular mineralization is shown to feed into areas of Prismatic development.
3. N204-type Deposit - N204 mineralization consists of fine crystalline mineralization deposited within the porosity of strati-bound layers below the main sequence known as the B-spongy horizon where intense dissolution resulted in the development of a fine dolomite breccia. This type of deposit has to date only been identified at N204. A related type of mineralization is found at N204 where Tabular-like mineralization occurs in a lower part of the barrier reef stratigraphy, in a horizon named the “B-spongy horizon” (Cominco Ltd. terminology). Here, precipitation of fine-crystalline dolomite resulted in the preferred dissolution of macro fossil components, resulting in the development of a distinct moldic porosity. Mineralization at the N204 deposit is wholly confined to this dissolution horizon.
Mineralization
Sulphide mineralization at Pine Point consists of three mineral species, in order of decreasing abundance: sphalerite, galena, and subordinate marcasite. Sulphide mineralization at Pine Point is developed in various textures and types that can broadly be classified into three groups and are specific to the sulphide species present. These are as follows:
1. Coliform sphalerite. This texture is the most common variety. It is fine-grained and banded with colours ranging from light beige to dark purple. This colour variation is due to the relative percentage of iron in the crystal lattice, with the dark brown variety having a higher iron content. Galena may be developed within the coliform banding; however, it is generally coarse-grained and crystallizes individual crystals sporadically developed within the coliform texture.
2. Coarse-grained and dendritic sphalerite. This texture is less common than the coliform variety but is well-developed throughout the property and may be intermixed with the coliform variety. Sphalerite is generally the darker brown variety, having a higher iron content. It is coarser-grained than the coliform variety.
3. Course-grained Galena. This texture is developed in regions between coliform sphalerite development, which can be demonstrated as a later phase. It can also occur without sphalerite, generally occurring in the core of the prismatic-style deposits and in the higher-grade keel of the tabular-style deposits.
4. Re-sedimented sulphides. This is a relatively minor texture. It is generally found in large pore spaces/caves within both deposit styles, and it appears to be a residual concentrate following the hydraulic reworking of previously precipitated sulphides. This results in a deposit of detrital sand, composed primarily of sphalerite and galena. Regrowth of sphalerite on the detrital grains can also be observed. This demonstrates the mechanical erosion of previously precipitated sulphides and the formation of detrital sulphides as part of the mineralizing process.
5. Massive marcasite. In many prismatic-style deposits, massive marcasite lenses are noted to occur in the immediate periphery of sphalerite and galena mineralization. These lenses are relatively small, in the range of 15 x 15 m as a maximum. They generally have a crosscutting characteristic to stratigraphy but can merge with marcasite horizons with a wider lateral extent. These lateral horizons tend to become more disseminated. Massive lenses of marcasite are noted to occur with tabular-style deposits; however, these are much rarer.
6. Disseminated to semi-massive marcasite. These generally occur in stratabound horizons with a wider lateral extent than lead and zinc mineralization. Weekly disseminated marcasite may be present with coliform and coarse-grained sphalerite. It may also occur with the hydrothermal alteration associated with mineralization.
7. Sphalerite and galena are present as coatings sponge fossil-moldic porosity and weakly disseminated in the host rock within the B-spongy horizon and specific to the N204 deposit. It is generally fine-graied.