Mono county, California, USA
The 100% owned Long Valley Project represents a gold development opportunity with a current NI 43-101 resource and historic positive preliminary economic results. The project displays a large gold resource, superb mining access, and excellent metallurgical extraction. Long Valley is one of the few development-ready precious metals resources in California, a stable jurisdiction with clear permitting processes and recent mine startups. Kore intends to employ modern exploration techniques to expand, upgrade, and develop the Long Valley deposit toward gold production.
Long Valley hosts a large near-surface gold-silver deposit 2.5 km long that is exposed on surface and provides excellent mining access. The gold deposit boasts a low strip ratio (1:1), broadly disseminated zones, and excellent oxide metallurgy averaging 79%. Gold-silver mineralization shows good continuity and includes zones of higher grade above 3.4 g/t Au.
Kore plans to upgrade and expand the resource through additional drilling, produce a geological model of the deposit, and advance engineering and environmental studies toward production permitting.
Primary MINERALIZATION present at long valley:
Kore’s 100% owned Long Valley gold development project covers 95 contiguous claims and an area of approximately 1,800 acres. The project was acquired from Vista Gold Corp. and was explored by Royal Gold in the 1980's and 1990's. The Company updated a NI43-101 resource in 2018 to supplement historic economic assessments of the project.
Long Valley is a near surface target that exhibits potential for expansion of the resource both laterally and at depth with consistent grades. The gold deposit boasts mineralization at surface, broadly disseminated zones, and excellent oxide metallurgy (with historic testing averaging 79%). We anticipate low cost mining due to the low strip ratio and shallow nature of the existing deposit.
We anticipate completion of a new economic assessment and updated resource model in 2019.
Property Description & Location
The Long Valley gold development project covers 728 ha in 95 contiguous unpatented mineral claims.
It is located in Mono County, east-central California, approximately 57 miles to the south of the town of Bridgeport and about 45 miles north of the town of Bishop, California. Both towns are connected by U.S. Highway 395, which passes a few miles west of the property. Access to the property from the highway is via a series of graded gravel roads. The claims are administered by the BLM on federally owned lands administered by the Inyo National Forest, U.S. Department of Agriculture.
The project was acquired from Vista Gold Corp. and was explored by Freeport, Standard Industrial Metals, Battle Mountain Gold, and Royal Gold in the 1980s and 1990s. An historic NI 43-101 Preliminary Economic Assessment was completed in 2008 and incorporates current California mining regulation.
early 1980’s: Standard Industrial Minerals Inc. discovered anomalous gold near a kaolinite clay mining operation NW of the current property.
1983-1984: Standard optioned the property to Freeport-McMoRan. Freeport drilled 8 shallow RC holes on the South Zone.
1985: Freeport dropped out of the option. Standard continued to drill and completed another 24 rotary holes on the South Zone.
1988: Royal Gold acquired the property under a lease/purchase option. Royal Gold drilled 52 air track holes on the South Zone. Metallurgical and engineering studies were also completed.
1990-93: Royal Gold and Battle Mountain formed a joint venture with Battle Mountain operating. Geological mapping, outcrop sampling and geophysical surveys completed. 59 RC holes were drilled. The South Zone was expanded and the Hilton and Southeast Zones were discovered. Battle Mountain dropped out of the JV in 1993.
1994-1997: Royal Gold completed 615 RC and 10 core holes on the Hilton Creek and Southeast Zones. A metallurgical study and engineering studies are also completed.
1997: Amax completed 46 RC and 10 core holes as part of a due diligence toward a possible JV. Most of the holes twinned earlier holes. Extensive re-assaying and check assaying was performed. Amax elected not to proceed with the JV due to a drop in gold price and a pending merger.
2000: Royal Gold returned the property to Standard in order to become a pure royalty company.
2003-2008: Vista Gold acquired an option to purchase the project and exercises its option for 100% of the property in 2007. A preliminary economic assessment (NI 43-101 compliant) report is completed in January 2008.
2017: Kore Mining Ltd. acquires 100% of the Long Valley project from Vista Gold.
Long Valley had a historical preliminary economic assessment performed in 2008, which projected an internal pre-tax NPV of US$102 million (US$800/oz gold price) on oxide ounces of gold only (approximately 535,400 ounces of gold projected to be recovered).
In 2017 Kore completed a ground-based magnetotelluric (MT) survey to better understand the characteristics of the epithermal mineralization at Long Valley. Interpretation of the MT survey combined with mapping and historical drilling will aid in the precision of drilling targets in the future.
Geologic Setting & Mineralization
The Long Valley deposit is contained entirely within the early Pleistocene-age Long Valley caldera, which has been dated at about 760,000 years old. The caldera is an elongated east-west oval depression measuring some 10 by 19 miles and is related to the eruption of the Bishop Tuff, which is mostly covered by younger rocks within the caldera.
The Long Valley gold deposit is located near the center of the caldera and is underlain by lithologic units related to the caldera formation and its subsequent resurgence. Associated with the resurgent doming is a sequence of interbedded volcaniclastic sedimentary rocks which were deposited in a lacustrine setting within the caldera. These rocks consist of sediment (siltstones through conglomerates) and debris-flow deposits, with local deposits of intercalated silica sinter and rhyolite flows and dikes. All of these lithologies have been altered and/or mineralized to variable degrees. Intruding the generally flat-lying lake sediments are several younger rhyolite domes that have been dated from 200,000 to 300,000 years in age.
The north-south trending Hilton Creek fault zone appears to define the eastern limit of the resurgent dome within the central part of the Long Valley caldera and extends outside the caldera to the south. This fault system is thought to control the distribution of gold mineralization in the Long Valley deposit. Offset along this fault appears to be variable and suggests that fault activity along this zone may be episodic in nature. Active hot springs, earthquakes, and very recent volcanism suggest that the area is still geologically active.
Gold and silver mineralization at Long Valley appears to fall under the general classification of an epithermal, low sulfidation type deposit. Several areas, termed the North, Middle, South, Southeast, and Hilton Creek zones, are mineralized with low grades of gold and silver; the North Zone lies outside of the current property boundary. The mineralized zones are generally north-south trending, up to 8,000 ft in length with widths ranging from 500 ft to 1,500 ft. The tabular bodies are generally flat-lying or have a shallow easterly dip. Mineralization is typically from 50 to 200 ft thick and, in the South and Southeast zones, is exposed at (or very near) the surface. The top of the Hilton Creek zone is generally covered by 20 to 50 ft of alluvium. The vast majority of the mineralization discovered to date is located in the Hilton Creek zone.
Drilling is widely spaced in and between the North, Middle, and South zones, and it may be possible that, with additional drilling, these zones may be shown to be contiguous with the better defined zones to the south.
Royal Gold generally defined the base of the oxidized zone as the last occurrence of oxide mineralization. Sulfide mineralization and mixed oxide-sulfide material also occurs above this boundary. The sulfide/oxide boundary occurs at depths between 150 and 250 ft and is often coincident with or slightly above the current water table.
Gold and silver mineralization is quite continuous throughout the zones and is well defined above ~0.010 oz Au/t. Within the continuous zones of low-grade (+0.010 oz Au/t) gold mineralization are numerous zones of higher grade mineralization (+0.050 oz Au/t), particularly in the Hilton Creek zone, which may relate to zones of enhanced structural preparation. Mineralized zones are typically correlated with zones of more intense clay alteration or argillization and/or silicification.
Kore recently commissioned an updated, pit-optimized resource estimate that increased gold ounces in the measured and indicated categories. We anticipate further resource expansion from our upcoming drill program. The deposit shows potential for expansion both laterally and at depth with consistent grades. The potential for deeper higher-grade feeder zones along the mineralization-controlling fault offers a compelling expansion target.
In 2018, mineral resources reported for the Long Valley property were modelled and estimated by Mine Development Associates (“MDA”) in accordance with the CIM Standards. The model for the resource was prepared in 2003 by MDA, with the current updated resource calculated on April 10, 2018. No drilling occurred on the property after the 2003 model was created. The resource estimate considered both a heap leach operation for oxide and transition material and a plant to recover sulfide material. Pit optimization parameters were developed for the different materials.
Gold resources that are contained in a $1,500 per ounce optimized pit were estimated by MDA for the Hilton Creek, Southeast, and South zones and are summarized in the table below*.
|Size (tonnes)||Grade (g/t)||Au (oz)||Source||Au Cutoff (g/t)|
|Total M&I||66,801,000||0.58||1,247,000||2018 Resource||0.156|
|Total Inferred||23,560,000||0.64||486,000||2018 Resource||0.156|
Resources reported as oxide in this report are the material situated above an oxide-sulfide boundary that was generally determined by recording the last occurrence of oxide minerals observed in the drill cuttings or core, and above a transition zone that occurs approximately between 150 and 200 feet below the surface. As such, not all material situated above this boundary can be considered as oxide in the context of metallurgical recovery, as it undoubtedly includes materials that will react differently metallurgically. One of the most important tasks to complete is the development of a model that better defines the metallurgical characteristics of the deposit and is planned as a next step by Kore.
Potential for resource expansion exists by connecting individual mineralized zones, discovery of higher grade fault-localized epithermal veins, and exploration of hypogene mineralization below depth of current drilling. This will be accomplished by applying more effective modern exploration concepts and techniques than those used 25 years ago.
Historical exploration focused on oxidized mineralization using a grid drilling strategy.
Primary ore controls were not established due, in part to RC drilling methods.
Resolving the position and geometry of high-grade zones can enhance economics and point to exploration targets at depth.
Mineralization is open at depth, to the north and between defined mineralization zones.
Project benefits from proximity to transport and power infrastructure.
Kore’s program will include:
Interpretation of recently completed Spartan MT geophysical survey
Assaying for silver using multi acid digestion (Metallurgical testing suggests higher silver grades are coincident with higher gold grades on the property)
A drill program being designed to infill near surface high grade areas, while providing information for engineering design (geotechnical, hydrogeological, metallurgical, and waste rock characterization)
Baseline environmental studies, updated environmental and archaeological studies, and engineering design planned
Process flowsheet design and metallurgical recovery will focus on optimizing 3-stage crushing with HPGR and agglomeration
Update resource model with new information from re-logging, drilling, and assays
Design mine plan around early mining of higher grade oxides for quick capital payback
Advance project towards permitting of oxide resource
The 2019 drill program will provide infill assays, material for metallurgical testing, improved geologic information, density data, and locations for groundwater monitoring wells. This information will result in an expanded resource and geologic model of the deposit and a new Preliminary Economic Assessment. These will facilitate advancing engineering and environmental studies towards permitting.
The last PEA was performed in 2008 and concluded a pre-tax NPV(5) of $102M and IRR of 63% at US$800/oz Au.** on oxide gold material only. With expanded resources, additional geologic information, and current gold prices, we expect improved economics from an updated PEA and rapid progress toward production.
Kore intends to complete a drill program as a next step with the objective of completing a pre-feasibility study in 2019.
*Technical Report and Resource Estimated for the Long Valley Project, Mono County, California, USA: April 5, 2018, by Niel Prenn of Mine Development Associates. Mineral resources are not mineral reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the mineral resource will be converted into mineral reserves. The estimate of mineral resources may be materially affected by environmental, permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues.
**Technical Report, Preliminary Assessment, Long Valley Project, Mono County, California, USA: January 9, 2008 by Neil Prenn, P.Eng and Thomas Dyer, P.Eng. of Mine Development Associates, Reno Nevada. Prepared for Vista Gold Corp. ("2008 PEA").
***Oxide only. Transition and sulfide cut-off grade 0.187 g/t.