GT Gold announces maiden Mineral Resource Estimate for Saddle North project, Tatogga property in British Columbia, Canada
VANCOUVER, British Columbia, July 06, 2020 (GLOBE NEWSWIRE) — GT Gold Corp. (TSX-V:GTT) (the “Company” or “GT Gold”) is pleased to announce a maiden Mineral Resource Estimate in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum (“CIM”) Definition Standards incorporated by reference in National Instrument 43-101 (“NI 43-101”) for the Saddle North project (“Saddle North”), Tatogga property in northern British Columbia, Canada.
Saddle North Mineral Resource Highlights:Indicated Resource of 298 Mt grading 0.28% copper, 0.36 g/t gold and 0.8 g/t silver for a total of 1.81 Mlb of copper, 3.47 Moz of gold and 7.58 Moz of silverInferred Resource of 543 Mt grading 0.25% copper, 0.31 g/t gold and 0.7 g/t silver for a total of 2.98 Mlb of copper, 5.46 Moz of gold and 11.64 Moz of silverAmenable to open pit as well as bulk underground mining methodsPotential for expansion with mineralization being open at depth as well as to the northwest and southeastThe Mineral Resource forms the basis for a Preliminary Economic Assessment (“PEA”) expected to be completed by the end of 2020“The company is pleased to announce another major milestone with the maiden mineral resource estimate for the Saddle North Project. We are proud of the value generated for our shareholders, especially considering this is one of the most recently discovered gold-copper porphyry world-wide, with the first borehole drilled as recently as late 2017,” stated Paul Harbidge, President and CEO. “The importance of having a geological model and a high quality of underlying data to more accurately segregate and estimate these resources will only play a stronger role as we move into our PEA work ahead. Entering the 2020 field season, we look forward to testing prospective greenfield targets in the Quash Pass area at Tatogga, in a region which is now beginning to show the signs of a newly emerging porphyry district in northern British Columbia.”The effective date of the Mineral Resource is July 6, 2020. A supporting NI 43-101 Technical Report will be filed on SEDAR at www.sedar.com within 45 days.These open pit and underground mine shape constrained Mineral Resources are summarized below in Table 1.Table 1: Saddle North Mineral ResourceNotes to Table 1: 1Net Smelter Return (“NSR”) ($/t) = (Cu% x 2204.62 lb/t x Cu Recovery x payable% x Cu CAD Price) + (Au g/t ÷ 31.1035 g/ounce x Au Recovery x Au CAD Price x payable%) + (Ag g/t ÷ 31.1035 g/ounce x Ag Recovery x Ag CAD Price x payable%)2All values in Canadian dollars unless otherwise statedDifferences may occur in totals due to roundingThe effective date for the Mineral Resource is July 6, 20203Transition-Sulphide boundary determined from visual logging (weak oxidation in transition material limited to fracture plane surfaces)The CIM Definition Standards (May 10, 2014) were followed for classification of Mineral ResourcesMineral Resources are reported using:Metal prices of USD $3.25/lb of copper, USD $1,500/oz of gold and USD $18/oz of silverAverage density of 2.80 g/cm3USD $/CAD $ exchange rate of 0.76Metallurgical recoveries of 88% for copper, 67% for gold and 58% for silverPayable metal net of smelter costs at 89%Resources constrained within an open pit shell optimized with the Lerchs-Grossman algorithm and the underground within a minable shape applicable to bulk mining were provided to the Qualified Person by Moose Mountain Technical Services:
– For open pit, mining costs of $2.30/t, with an additional incremental depth cost
– Processing, General and Administrative costs sum of $9.00/t
– Open pit wall angle of minus 45 degrees
– 1NSR ($/t) incremental cut-off of $9.00 for the open pit
– For underground, a bulk mining shape based on a NSR cut-off of $16.00/t. The lateral and vertical continuity of the mineral resource provides a geometric configuration that is amenable to bulk tonnage underground mining methods. Geological ModelThe Saddle North Mineral Resource is delineated by forty-one HQ and NQ sized diamond boreholes totaling 31,401 metres. Topographic control was from a detailed LiDAR survey dataset, flown October 2018.The geological model (see press release dated April 28, 2020) was used to domain and constrain mineralization. Mineralization is predominantly hosted in a suite of nested monzonite to quartz-monzonite porphyries. The tenor of copper, gold and silver mineralization has a strong correlation with the intensity of potassic alteration, with high-grade domains associated with strong potassic alteration grading outwards to low-grade mineralization in weak potassic alteration domains. Mineralization is associated with chalcopyrite and pyrite. Metal tenor improves with increasing density of porphyry-style A-veins. The mineralized porphyries and associated alteration and mineralization occur in the hanging wall of the northwest orientated Poelzer fault which dips steeply at 85 degrees to the southwest. The pipe-like mineralized system measures 1.2 kilometres north-south by 0.85 kilometres east-west by 1.6 kilometres vertically. Phyllic (quartz-sericite-pyrite) alteration occurs predominantly in the upper levels of the system and on the shoulders of the potassic alteration. There is a pervasive late chlorite-sericite alteration and minor to trace argillic alteration overprint. The mineralized porphyries are intruded by two late stage inter-mineral porphyries and a number of decimetre to metre scale dykes. Late-stage, centimetre scale, quartz-carbonate veins crosscut the earlier porphyry mineralization. High-grade gold and occasionally copper mineralization are commonly associated with these late quartz-carbonate veins but have not been modelled as the continuity of these veins cannot be established. The porphyry system is hosted in the Upper Triassic Stuhini Group volcano-sedimentary sequences, which in turn is overlain by the Late Jurassic Hazelton sedimentary sequences.Geology was modelled using Leapfrog Geo incorporating logged lithology and alteration front contacts from which three-dimensional wireframe models were constructed. Potassic alteration logged intervals were used to construct the weak, moderate and strong alteration wireframes. Key lithologies for use in the mineral resource estimate were the porphyries, inter-mineral porphyries and dykes which were all used to construct three-dimensional wireframes.Mineral Resource EstimateEstimation domains were derived using univariate exploratory data analysis to group like populations which showed consistency for all three metals and were therefore used for all three metal estimations. Three lithological domains were constructed for porphyries P1, P2/P4 and P3/P5. Weak, moderate and strong potassic alteration intensity domains were constructed. Box plots and cumulative frequency distributions were compared to delineate the eight unique mineralized domains, noting there was no strong potassic alteration in porphyry P1. Contact plots were used to define soft boundaries between mineralized domains with hard contacts at inter-mineral porphyries and dykes. In addition, no grades were estimated in the footwall of the Poelzer fault.The average sampling length of the Saddle North porphyry system is 1.5 metres (approximately 39% of the sample data). Assay grades were capped at 3.0% for copper, ranging between 1.75 g/t to 7.0 g/t for gold and between 2.0 g/t to 8.0 g/t for silver, for the different intensities of potassic alteration. The capping of assays in the weak and moderate potassic alteration zones reduced the impact of the late stage, high-grade gold in quartz-carbonate veins, described above. Capped assays were composited at 15 metres, breaking at lithological and potassic alteration domain boundaries.Variography (correlograms) were used to model the grade continuity and to determine the search ellipse dimensions for the interpolation of copper, gold and silver separately within the combined potassic alteration domain. The geological model wireframes were key inputs to the resource estimate to define contacts between all mineralized porphyries and all potassic alteration fronts. The azimuth and dip of the potassic alteration fronts were measured and applied at the block scale in the estimation of block grades. Estimations were done using Maptek Vulcan three-dimensional software.Mineral resource model blocks measured 15 metres in all dimensions. Metal grades were estimated using ordinary kriging in ten passes with search ranges increasing from 40 x 60 x 25 metres to 200 x 350 x 50 metres. For indicated material, estimation passes required a minimum of two holes using a minimum of six samples and a maximum of nine. Inferred material required a minimum of a single borehole using a minimum of three samples and a maximum of nine within modelled geological domains to half (67.5 m) the borehole spacing. Approximately 13% of inferred mineral resource block grades were estimated using a single borehole.Grade estimates were controlled by high-grade and low-grade indicators. These indicators were used to identify grade populations within the potassic alteration zones. High-grade composites within populations were spatially constrained to within 60 metres of drilling.Block model densities were determined based on 7,780 measurements. The average density per lithology unit was assigned to the corresponding blocks.The block model was validated separately for each metal, copper, gold and silver in three ways:Visual comparison of block values with underlying borehole composite valuesComparison to declustered composites using swath plots and histogramsComparison with an inverse distance estimateMineral resources classified as indicated required a minimum of three boreholes within a distance of 135 x 135 x 50 metres. As described above in grade estimation, approximately 61% of the indicated blocks used two holes at search distances less than 135 x 135 x 50 metres. Mineral resources classified as inferred required a minimum of two boreholes within a distance of 200 x 350 x 50 metres or a minimum of one borehole within a search distance of 67.5 x 67.5 x 50 metres. Approximately 13% of inferred blocks were classified by one borehole. Classification search distances were based on variography.NSR cut-off sensitivities for the Saddle North Mineral Resource are presented in Table 2.
Table 2: Mineral Resource Sensitivity to changes in NSR Cut-Off1, 2