Idaho’s Conservation

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100% Owned Subsidiary of Integra Resources


The following content was created from the attached document:


(The three mountains intended to be mined by Integra Resources)


Mine Development Associates (“MDA”), a division of RESPEC has supervised the preparation of this technical report and Pre-Feasibility Study (“PFS”) of the DeLamar gold – silver project, located in Owyhee County, Idaho, at the request of Integra Resources Corp. (“Integra”), a Canadian company listed on the TSX Venture Exchange (TSX.V:ITR) and the NYSE American Exchange (NYSE:ITRG). The DeLamar project encompasses the DeLamar and Florida Mountain deposit areas. Both deposit areas have been subject to historical underground mining in the late 1800s and early 1900s, as well as late 20th century open-pit mining. The most recent open-pit mining, which ceased in 1998, was conducted by Kinross Gold Corporation (“Kinross”).

The effective date of this technical report is January 24, 2022.

Property Description and Ownership The DeLamar project includes of 790 unpatented lode, placer, and millsite claims, and 16 tax parcels comprised of patented mining claims, as well as certain leasehold and easement interests, that cover approximately 8,673 hectares (21,431 acres) in southwestern Idaho, about 80 kilometers (50 miles) southwest of Boise. The property is approximately centered @ 43°00′48″N, 116°47′35″W, within portions of the historical Carson (Silver City) mining district, and it includes the formerly producing DeLamar mine last operated by Kinross. 

The total annual land-holding costs are estimated to be $473,244. All mineral titles and permits are held by the DeLamar Mining Company (“DMC”), an indirect, 100% wholly owned subsidiary of Integra that was acquired from Kinross through a Stock Purchase Agreement in 2017.

(21,431 acres & two mountains encompass the area intended to be mined)

A total of 284 of the unpatented claims were acquired from Kinross, 101 of which are subject to a 2.0% net smelter returns royalty (“NSR”) payable to a predecessor owner. This royalty is not applicable to the current project resources and reserves. There are also eight lease agreements covering 33 patented claims and five unpatented claims that require NSR payments ranging from 2.0% to 5.0%. One of these leases covers a small portion of the DeLamar area resources and one covers a small portion of the Florida Mountain area resources and reserves, with 5.0% and 2.5% NSRs applicable to maximums of $50,000 and $650,000 in royalty payments, respectively. The property includes 1,561 hectares (3,857.2 acres) under seven leases from the State of Idaho, which are subject to a 5.0% net smelter returns production royalty plus annual payments of $27,282. The State of Idaho leases include very small portions of both the DeLamar and Florida Mountain resources and reserves. Kinross had retained a 2.5% NSR royalty that applies to those portions of the DeLamar area claims that are unencumbered by the royalties outlined above. The royalty was subsequently sold to Maverix Metals Inc (“Maverix”). The Maverix royalty applies to more than 90% of the current DeLamar area resources and reserves, but this royalty will be reduced to 1.0% upon Maverix receiving total royalty payments of CAD $10,000,000. DMC also owns mining claims and leased lands peripheral to the DeLamar project described above. These landholdings are not part of the DeLamar project, although some of the lands are contiguous with those of the DeLamar and Florida Mountain claims and state leases. The DMC lands peripheral to the DeLamar project have no mineral resources or mineral reserves. The DeLamar project historical open-pit mine areas have been in closure since 2003. While a substantial amount of reclamation and closure work has been completed to date at the site, there remain ongoing water-management activities, monitoring, and reporting. A reclamation bond of $2,778,929 remains with the Idaho Department of Lands (“IDL”) and a reclamation bond of $100,000 remains with the Idaho Department of Environmental Quality. Additional reclamation bonds in the total amount of $589,144 have been placed with the U.S. Bureau of Land Management (“BLM”) for exploration activities and groundwater well installation on public lands. There are also reclamation bonds with the IDL in the total amount of $86,900 for exploration activities on IDL leased lands.

(Courtesy of Google Earth as seen from space)

Exploration & Mining History

Total production of gold and silver from the DeLamar project area is estimated to be approximately 1.3 million ounces of gold and 70 million ounces of silver from 1891 through 1998, with an additional but unknown quantity produced at the DeLamar mill in 1999. From 1876 to 1891, an estimated 1.025 million ounces of gold and 51 million ounces of silver were produced from the original De Lamar underground mine and the later DeLamar open-pit operations. At Florida Mountain, nearly 260,000 ounces of gold and 18 million ounces of silver were produced from the historical underground mines and late 1990s open-pit mining. Mining activity began in the area of the DeLamar project when placer gold deposits were discovered in early 1863 in Jordan Creek, a short distance upstream from what later became the town site of De Lamar.

During the summer of 1863, the first silver-gold lodes were discovered in quartz veins at War Eagle Mountain, to the east of Florida Mountain, resulting in the initial settlement of Silver City. Between 1876 and 1888, significant silver-gold veins were discovered and developed in the district, including underground mines at De Lamar Mountain and Florida Mountain. A total of 553,000 ounces of gold and 21.3 million ounces of silver were reportedly produced from the De Lamar and Florida Mountain underground mines from the late 1800s to early 1900s. The mines in the district were closed in 1914, following which very little production took place until gold and silver prices increased in the1930s. Placer gold was again recovered from Jordan Creek from 1934 to 1940, and in 1938 a 181 tonne-per-day flotation mill was constructed to process waste dumps from the De Lamar underground mine. The flotation mill reportedly operated until the end of 1942. Including Florida Mountain, the De Lamar – Silver City area is believed to have produced about 1 million ounces of gold and 25 million ounces of silver from 1863 through 1942. During the late 1960s, the district began to undergo exploration for near-surface bulk-mineable gold-silver deposits, and in 1977 a joint venture operated by Earth Resources Corporation (“Earth Resources”) began production from an open-pit, milling and cyanide tank-leach operation at De Lamar Mountain, known as the DeLamar mine. In 1981, Earth Resources was acquired by the Mid Atlantic Petroleum Company (“MAPCO”), and in 1984 and 1985 the NERCO Mineral Company (“NERCO”) successively acquired the MAPCO interest and the entire joint venture to operate the DeLamar mine with 100% ownership. NERCO was purchased by the Kennecott Copper Corporation (“Kennecott”) in 1993.

Two months later in 1993, Kennecott sold its 100% interest in the DeLamar mine and property to Kinross, and Kinross operated the mine, which expanded to the Florida Mountain area in 1994. Mining ceased in 1998, milling ceased in 1999, and mine closure activities commenced in 2003. Closure and reclamation were nearly completed by 2014, as the mill and other mine buildings were removed, and drainage and cover of the tailing facility were developed. Total open-pit production from the DeLamar project from 1977 through 1998, including the Florida Mountain operation, is estimated at approximately 750,000 ounces of gold and 47.6 million ounces of silver, with an unknown quantity produced at the DeLamar mill in 1999. From start-up in 1977 through to the end of 1998, open-pit production in the DeLamar area totaled 625,000 ounces of gold and about 45 million ounces of silver. This production came from pits developed at the Glen Silver, Sommercamp – Regan (including North and South Wahl), and North DeLamar areas. In 1993, the DeLamar mine was operating at a mining rate of 27,216 tonnes (30,000 tons) per day, with a milling capacity of about 3,629 tonnes (4,000 tons) per day. In 1994, Kinross commenced open-pit mining at Florida Mountain while continuing production from the DeLamar mine. The ore from Florida Mountain, which was mined through 1998, was processed at the DeLamar facilities. Florida Mountain production in 1994 through 1998 totaled 124,500 ounces of gold and 2.6 million ounces of silver. Exploration of the DeLamar project by Integra commenced in 2017. Since then, Integra has carried out geophysical and geochemical exploration programs, and on-going geologic mapping and exploration drilling programs. Drilling was on-going as of the effective date of this report.

Developing the DeLamar Gold project located in southwestern Idaho:

Integra Resources Corp.

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Integra Resources is a development-stage mining company focused on the exploration and de-risking of the past producing DeLamar Gold-Silver Project in Idaho, USA. Integra Resources is led by the management team from Integra Gold Corp. which successfully grew, developed and sold the Lamaque Project, in Quebec, for C$600 M in 2017. Since acquiring the DeLamar Project, which includes the adjacent DeLamar and Florida Mountain gold and silver Deposits, in late 2017, the Company has demonstrated significant resource growth and conversion while providing a robust economic study in its maiden Preliminary Economic Assessment. The Company is currently focused on resource growth through brownfield and greenfield exploration and the start of advanced studies designed to de-risk the DeLamar Project and move it towards a potential development decision.

Geology & Mineralization

The DeLamar project is situated in the Owyhee Mountains near the east margin of the mid-Miocene Columbia River – Steens flood-basalt province and the west margin of the Snake River Plain. The Owyhee Mountains comprise a major mid-Miocene eruptive center, generally composed of mid-Miocene basalt flows intruded and overlain by mid-Miocene rhyolite dikes, domes, flows and tuffs, developed on an eroded surface of Late Cretaceous granitic rocks. The DeLamar mine area and mineralized zones are situated within an arcuate, nearly circular array of overlapping porphyritic and flow-banded rhyolite flows and domes that overlie cogenetic, precursor pyroclastic deposits erupted as local tuff rings. Integra interprets the porphyritic and banded rhyolite flows and latites as composite flow domes and dikes emplaced along regional-scale northwest-trending structures. At Florida Mountain, flow-banded rhyolite flows and domes cut through and overlie a tuff breccia unit that overlies basaltic lava flows and Late Cretaceous granitic rocks. Gold-silver mineralization occurred as two distinct but related types: (i) relatively continuous, quartz filled fissure veins that were the focus of late 19th and early 20th century underground mining, hosted mainly in the basalt and granodiorite and to a lesser degree in the overlying felsic volcanic units; and (ii) broader, bulk-mineable zones of closely-spaced quartz veinlets and quartz-cemented hydrothermal breccia veins that are individually continuous for only a few meters/feet laterally and vertically, and of mainly less than 1.3 centimeters (0.5 inches) in width – predominantly hosted in the rhyolites and latites peripheral to and above the quartz-filled fissures. This second style of mineralization was mined in the open pits of the late 20th century DeLamar and Florida Mountain operations, hosted primarily by the felsic volcanic units.

The fissure veins mainly strike north to northwest and are filled with quartz accompanied by variable amounts of adularia, sericite or clay, ± minor calcite. Vein widths vary from a few centimeters to several meters, but the veins persist laterally and vertically for as much as several hundreds of meters. Principal silver and gold minerals are naumannite, aguilarite, argentite, ruby silver, native gold and electrum, native silver, cerargyrite, and acanthite. Variable amounts of pyrite and marcasite with very minor chalcopyrite, sphalerite, and galena occur in some veins. Gold- and silver-bearing minerals are generally very fine grained. The gold and silver mineralization at the DeLamar project is best interpreted in the context of the volcanic hosted, low-sulfidation type of epithermal model. Various vein textures, mineralization, alteration features, and the low contents of base metals in the district are typical of shallow low-sulfidation epithermal deposits worldwide.

(Areas currently scarred by Integra’s drill testing)

Metallurgical Testing

Metallurgical testing by Integra, generally conducted at McClelland Laboratories (“McClelland”) during 2018 through 2021, has been used to select preferred processing methods and estimate recoveries for oxide, mixed and non-oxide mineralization from both the DeLamar and Florida Mountain deposits. Samples used for this testing, primarily drill hole composites from 2018 through 2020 Integra drilling, were selected to represent the various material types contained in the current resources from both the DeLamar and Florida Mountain deposits. Composites were selected to evaluate effects of area, depth, grade, oxidation, lithology, and alteration on metallurgical response. Bottle-roll and column-leach cyanidation testing on drill core composites from both the DeLamar and Florida Mountain deposits and on bulk samples from the DeLamar deposit have shown that the oxide and mixed material types from both deposits can be processed by heap-leach cyanidation. These materials generally benefit from relatively fine crushing to maximize heap-leach recoveries and a feed size of 80% -12.7mm (0.5 inches) was selected as optimum. Expected heap-leach gold recoveries for the oxide mineralization from both deposits (DeLamar and Florida Mountain) are consistently high (70% – 89%). Heap leach gold recoveries for the mixed mineralization are expected to average 72% for Florida Mountain and to range from 45% to 63% for the DeLamar deposit. Heap leach silver recoveries from the Florida Mountain oxide and mixed materials are expected to average 49% and 47%, respectively. Expected heap-leach silver recoveries from the DeLamar material are highly variable (11% to 74%), but generally low. A significant portion of the DeLamar oxide and mixed mineralization will require agglomeration pretreatment using cement, because of elevated clay content. None of the Florida Mountain heap-leach material is expected to require agglomeration.

(Some of the equipment currently located @ DeLamar)

Metallurgical testing (primarily flotation and agitated cyanidation) has shown that the DeLamar non-oxide materials respond well to flotation at a moderate grind size (150 microns) for recovery of gold and silver to a flotation concentrate. The resulting flotation concentrate responds well to cyanide leaching after very fine regrinding (20 microns) for recovery of contained silver. Some gold is also recovered by cyanide leaching of the reground flotation concentrate, but those recoveries generally are low. Mineralogical examination and metallurgical testing have shown that these materials contain significant amounts of gold that are locked in sulfide mineral particles, which require oxidative pretreatment of sulfide minerals for liberation of gold before high cyanidation gold recoveries can be obtained. Expected recoveries from the DeLamar non-oxide mineralization in the planned mill circuit, consisting of grinding, flotation concentrate regrinding and cyanide leach, range from 28% to 39% for gold and from 64% to 87% for silver.

(The $282 million dollar prep work created this open-air “Leach-Heap” )

Metallurgical testing has shown that the non-oxide mineralization from the Florida Mountain deposit responds well to upgrading by flotation at a moderate grind size (150 microns) and cyanidation gold and silver recoveries from the resulting concentrates can be maximized by very fine regrinding (20 microns). In contrast to the DeLamar non-oxide materials, oxidative pretreatment of contained sulfide minerals is not required to achieve high cyanidation gold recoveries from the Florida Mountain non-oxide feeds. Recoveries expected from the Florida Mountain non-oxide mineralization in the planned mill circuit vary with feed grade, but generally are high, with maximum recoveries of 87% gold and 77% silver.

Integra Resources DeLamar Project

(Butch Otter approves of this process…OMG)

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Mining Methods

The PFS presented in this report considers open-pit mining of the DeLamar and Florida Mountain goldsilver deposits. Mining will utilize 23-cubic meter (30-cubic yard) hydraulic shovels along with 13-cubic meter (16.7-cubic yard) loaders to load 136-tonne capacity haul trucks. The haul trucks will haul waste and ore out of the pit and to dumping locations. Due to the length of ore hauls, the ore will be stockpiled near the pits followed by loading into a Railveyor system which will convey the ore into a crusher. The Railveyor system will be supplemented with haul trucks on an as needed basis. Waste material will be stored in waste-rock storage facilities (“WRSFs”) located near each of the Florida Mountain and DeLamar deposits, as well as backfilled into pits where available. The exception is the Milestone pit, from which waste material will be fully utilized for construction material for the tailing storage facility (“TSF”). Production scheduling was completed using Geovia’s MineSched™ (version 2021) software. Proven and Probable reserves along with waste material inside pit designs previously discussed were used to schedule mine production. The production schedule considers the processing of DeLamar and Florida Mountain oxide and mixed material by crushing and heap leaching, with some of the DeLamar material requiring agglomeration prior to leaching. DeLamar and Florida Mountain non-oxide material would be processed using flotation followed by cyanide leaching of the flotation concentrate. An autonomous Railveyor light-rail haulage system will be used to transport ore from the open pits to the crusher facility. Utilizing the Railveyor system allows the opportunity to realize cost savings compared to typical truck haulage. This system, in conjunction with the planned solar and liquid natural gas electrical microgrid will reduce the overall fuel consumption and carbon footprint of the project. The PFS has assumed owner mining instead of the more expensive contract mining. The production schedule was used along with additional efficiency factors, performance curves, and productivity rates to develop the first-principal hours required for primary mining equipment to achieve the production schedule. Primary mining equipment includes drills, loaders, hydraulic shovels, and haul trucks. Support, blasting, and mine maintenance equipment will be required in addition to the primary mining equipment.

Processing & Recovery Methods

This PFS envisions the use of two process methods for the recovery of gold and silver:

• Lower-grade oxide and mixed materials will be processed by crushed-ore cyanide heap leaching; and

• Non-oxide material will be processed using grinding followed by flotation, and very fine grinding of flotation concentrate for agitated cyanide leaching.

Heap-leach and milling ores will be coming from both the Florida Mountain and DeLamar deposits. Pregnant solutions from the heap-leach operation and from the milling operation will be processed by the same Merrill-Crowe zinc cementation plant. Processing will start with heap leaching in the first two years of operation. Milling of higher-grade non-oxide ore will start in the third year of operation. Both Florida Mountain and DeLamar oxide and mixed ore types have been shown to be amenable to heapleach processing following crushing.

Material will be crushed in three stages to a nominal size of 80% finer than (P80) 12.7-millimeter (0.5 inches), at a rate of 35,000 tonnes per day. About 45% of DeLamar ore is expected to require agglomeration. Crushed and prepared ore will be transferred to the heap-leach pad using overland conveyors and stacked on the heap using portable or grasshopper conveyors and a radial stacking system. Pregnant leach solution will be collected at the base on the heap leach and transferred to the Merrill-Crowe processing plant for recovery of precious metals by zinc precipitation. The precipitate will be filtered, dried, and smelted to produce gold and silver doré bullion for shipment off site. The milling process will start with primary crushing of the ore to a nominal P80 of 120 millimeter (4.72 inches), followed by grinding in a SAG mill-ball mill circuit to a P80 of 150 microns. The ball mill discharge will be pumped to hydrocyclones, with the hydrocyclone overflow advancing to flotation and the underflow returning to the ball mill. The flotation circuit will produce a sulfide concentrate that will recover gold and silver from the ore. This flotation concentrate will be reground to a nominal P80 of 20 microns before being leached in agitated leach tanks. Pregnant solution will be separated using a CCD circuit that employs dewatering cyclones and thickeners. The pregnant solution is then sent to the Merrill-Crowe plant and gold smelting facility to produce gold and silver doré bullion. The flotation tailing stream will be thickened and pumped to the tailing storage facility. The concentrate leach residue will be sent to cyanide destruction, then stored in a separate concentrate leach tailing storage facility.

Florida Mountain Update

(It’s about the money NOT the Mountains)

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Capital & Operating Costs

Table 1.7 summarizes the estimated capital costs for the project. The life of mine (“LOM”) total capital costs are estimated as $589.5 million, including $307.6 million in preproduction capital (including working capital and reclamation bond) and $281.8 million for expansion and sustaining capital. Sustaining capital includes $30.8 million in reclamation costs. The estimated capital costs are inclusive of sales tax, engineering, procurement and construction management (“EPCM”) and contingency.

Table 1.8 shows the estimated LOM operating costs for the project. Operating costs are estimated to be $12.93 per tonne processed for the LOM. This includes mining costs, which are estimated to be $1.90 per tonne mined. The total cash cost is estimated to be $923 per ounce of gold equivalent and site level all-in sustaining costs are estimated to be $955 per ounce of gold equivalent.

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