St Andrew Goldfields Ltd

Holt Mine

Summary

Nov 1, 2013

SAS has 100% ownership interest in the Holt-Holloway properties. The Holloway Mine and Holt Mine and Mill are located at the eastern end of SAS' land package in the Timmins Mining District, northeastern Ontario. The Holt-Holloway property package includes an irregularly shaped, east-west elongated assemblage of claims, patents, and mining leases that more or less straddle Ontario Provincial Highway 101 for about 52 km beginning east of Matheson in Michaud and McCool Townships and extending into Stoughton and Marriott Townships at the Québec border. The Holt and Holloway mines are located approximately 45 km northeast of Kirkland Lake and 52 km east of Matheson, Ontario. The Holt-Holloway land package comprises 48 separate property elements totalling 691 claims distributed as 257 mineral claims, 176 leased claims and 258 patented claims. The aggregate area is 15,172 ha (approximately 37,000 acres). All of the properties are in good standing. 

 

 

History

Holt-McDermott History (now referred to as the Holt Mine) : In 1922 P.A. McDermott discovered gold in northwestern Holloway Township and over the next four years conducted trenching and limited drilling on the prospect. McDermott Gold Mines Ltd. was incorporated and eventually ten contiguous claims were patented. A small drill program was carried out in 1937 but no further work was done until Sylvanite Gold Mines Ltd. optioned the property in 1948-1950 and drilled 11 holes totalling 925 metres along 76 metres of strike. In 1950 McDermott Gold Mines Ltd. became McDermott Mines Ltd. ("McDermott"). In 1985, a 420 metres exploration shaft was developed and a production decision made in late 1986 with production at 1,400 tpd beginning in 1988. The Holt-McDermott mill (renamed as the Holt Mill) was expanded in 1988 and 2001 and increased the throughput to 2,500 tpd and 3,000 tpd respectively. In October 2004, Newmont acquired the Holt Mill and mine assets from Barrick Gold Corporation ("Barrick"). In September 2004 the mine was shut down, having produced 1.32 million ounces of gold from 7.48 Mt of ore grading 5.9 g/t Au.
In November 2006, SAS acquired from Newmont all of the shares of its wholly owned subsidiary Holloway Mining Company, which owned the Holloway-Holt gold mines. On January 1, 2007 St Andrew amalgamated with Holloway Mining Ltd. (formerly Holloway Mining Company) to retain 100% interest in the Holloway and Holt properties.

 

Geology and Mineralization

At the Holt Mine, mineralized zones that have been historically mined are hosted by the McDermott shear zone, a 10 metres to 50 metres wide south-southeast dipping carbonate-sericite-chlorite ± albite altered ductile D3-D4 shear zone, which is hosted by otherwise massive and generally low strain mafic volcanic rocks. The McDermott shear zone has been traced laterally for approximately 10 km along strike, joining the Destor-Porcupine corridor to the northeast. It has been traced by drilling at least eight kilometres west of the Holt Mine headframe. The shear zone may be localized along an older D2 thrust plane that has structurally emplaced lenses of fine-grained clastic sedimentary units along it. Principal mineralized zones that have been mined to date along the structure include the South, C-104, McDermott, Worvest/Three Star, Mattawasaga, and C-97 zones, which occur over a strike length of three kilometres and have been mined to depths of over one kilometre below surface. More recently, the C-103, Zone 4 and Zone 6 gold mineralization has been identified along these geologic structures and are host to the bulk of the existing gold mineralization. All but the South Zone and Zone 4 occur in steeply south dipping sections of the shear zone. The South Zone and Zone 4 occur where the shear zone rolls to moderate to shallow southerly dips(1). Prominent within the Holt Mine geology are two northeast to east-northeast trending brittle faults, the Ghostmount and the McKenna. Although once interpreted as mineralization controlling structures, they offset mineralization and are in fact the youngest structural elements in the region(2).

(1) Rhys, D.A., Structural study of the Holloway and Holt-McDermott deposits, Ontario, with exploration implications; unpublished report for Newmont Canada Ltd., 2005a. (2) Ibid 2005a


Mineralization frequently occurs within the upper (hanging-wall/south) portions of the McDermott shear zone, often in areas where the structure defined by its carbonate-sericite-quartz altered high strain zone widens from a thickness of generally less than 10 metres to locally more than 50 metres wide. The widening may in part be controlled by the interaction of the shear zone with lenses of carbonaceous sedimentary rocks in its footwall. Mineralization occurs in massive to banded quartz-carbonate-pyrite-albite alteration that occurs within the McDermott shear zone and may extend a short distance into adjacent, unfoliated, massive mafic volcanics. Diffuse quartz veinlet networks and matrix are commonly developed, locally imparting breccia textures in sheared rocks. The apparent overprinting of foliation by alteration, and rotation of shear zone fabrics in breccia fragments, collectively suggest that mineralization overprints portions of the McDermott shear zone, and that it formed during or after most shear zone fabric development. An early phase of hematite-bearing carbonate-albite-quartz alteration is often preserved as lenses and domains within and adjacent to the Holt Mine mineralized zones.


Zones 4 and 6 at the Holt Mine have a well established higher grade gold zone (i.e. >3 g/t Au) related to a zone of more intense alteration, including sericite, chlorite, hematite and silicification, and elevated concentrations of sulphides within an overall lower grade envelope. These higher grade zones, typically three to five metres thick, are almost exclusively located along the hanging wall of the deposit, against the Ghostmount fault or any associated fault splay. The zones typically extend over 100 metres along strike and 100 metres down dip.


Native gold in mineralized zones at the Holt Mine occurs as fine grains spatially associated with pyrite, typically located in fractures, on grain boundaries, or encapsulated in pyrite grains. Microscopically, gold grain distribution can be clustered, however, assays do not reveal erratic or "nuggety" gold concentrations. Gold values in mineralized zones die out laterally, over several metres within the envelope of altered rock. There is generally a fairly sharp boundary on the hanging-wall side, but a more gradational lessening of values on the footwall side. This is particularly evident in Zone 4 and less evident in Zone 6 where the contacts of the mineralization are generally sharp with the surrounding mafic volcanic rocks.


Mineralized zones at the Holt Mine display two pronounced shoot plunges: (a) moderate to steep east plunges that outline the major zones, and (b) alignment of zones and chains of small mineralized shoots along shallow west plunging axes. The latter plunge is parallel to the plunge line of dip changes in the McDermott shear zone.


The reader is referred to the 2013 Holt-Holloway Technical Report for an extensive discussion of the geology of the Holt-Holloway property package.

 

Mineral Reserves and Resources

Mineral Reserves Estimate, December 31, 2012

 

Notes:

• Mineral Reserves are excluded from the Mineral Resources; Mineral Reserves as of December 31, 2011 were included in the Measured and Indicated Resources;
• Mineral Reserves were estimated by Management according to CIM Definition Standards -- November 2010;
• Mineral Reserves were estimated using an average long-term gold price of US$1,400 per ounce and an exchange rate of C$1.00 = US$1.00;
• Mineral Reserves for Holt were estimated using a cut-off grade of 3.0 g/t Au; Mineral Reserves included in the 2013 mining plan were estimated using an average gold price of US$1,600 per ounce and an exchange rate of C$1.00 = US$1.00;
•  Tonnes and gold ounce information is rounded to the nearest thousands and as a result, totals may not add exactly.

 

Mineral Resource Estimate, December 31, 2012


Notes:

• Mineral Resources are exclusive of Mineral Reserves; Mineral Reserves as of December 31, 2011 were included in the Measured and Indicated Resources;
• Mineral Resources were estimated by Management according to CIM Definition Standards -- November 2010
• Mineral Resources were estimated using an average long-term gold price of US$1,500 per ounce and an exchange rate of C$1.00 = US$1.00;
• Mineral Resources were estimated using a cut-off grade of 2.5 g/t Au ;
• Tonnes and gold ounce information is rounded to the nearest thousands and as a result, totals may not add exactly.

 

Development and Mining

The Holt Mine is accessed by a timbered rectangular three compartment shaft to a depth of 350 metres and four compartments to a depth of 1,195 metres. The ore zones are accessed by track drifts from the shaft, and all access within the zones are trackless ramps and sublevels. The Holt Mill was constructed in 1988, originally designed for a throughput of 1,360 tpd. Expansions in 1988 and 2001 increased the throughput to 2,500 tpd and 3,000 tpd respectively. Surface ore storage totals 4,900 tonnes in three silos. There is a grinding circuit, two cyclone cluster circuits, a thickener, and a Carbon-in-Leach ("CIL") circuit within the plant facilities.

 

Holt Mine - Mining Methods

The primary mining method employed by predecessor operators was longhole mining, used with either delayed backfill or remnant pillars left for stability. Stopes are typically 12.5 metres to 25.0 metres along strike, and 10 metres to 30 metres high. Broken ore is mucked from draw points and hauled to an internal ore pass using 3.5 yd³ scoop trams. From the ore passes, ore is trammed to the main shaft ore pass using 4.5 tonne rail cars. All ore is fed through an underground jaw crusher located just above the shaft loading pocket. From there, crushed ore is hoisted via the shaft to the surface in 8 tonne skips. The first zone mined in 2011 was the C-103 Zone, which was located below the 1075m Level. This zone was extracted employing the mining method described above. Production for 2012 was derived mainly from Zone 4, as well as C-104, and pre-production ore from Zone 6. Drilling commenced at Zone 6 in the second half of 2012 in preparation for production in 2013.


Mining methods may vary from longhole, cut and fill, and Alimak mining as ore geometry and ground conditions dictate.


Longhole mining typically requires two excavations within the ore at different elevations below surface, (15 metres to 30 metres apart). Holes are drilled between the two excavations and loaded with explosives. The holes are blasted and the ore is removed from the bottom excavation.


Cut and fill mining is a method of short hole mining where the ore is mined in horizontal or slightly inclined slices, and then filled with waste rock. As an option, fill may be consolidated with a binder (usually cement), or left unconsolidated. Cut and fill mining is a selective method, which allows for higher ore recovery and lower dilution.


Alimak mining is a version of longhole mining performed off of an Alimak platform. This type of mining is preferable when there is no top access and the ore zone is more linear in nature thereby lending itself to Alimak raising as an initial slot into the ore. Variations of this method are used worldwide; however the most popular is to employ longholes drilled sub-horizontally and allow the blasted muck to build up in the excavation in order to provide wall support as in shrinkage mining. The broken ore is removed from the drawpoint(s) and transported to the ore pass.

 

Exploration

Based on aeromagnetic patterns, and the locations of known alteration-high strain zones, examination of property geological and geophysical maps, in combination with known drill hole data, suggests that several east-northeast trending shear zones are developed across the area, including at least three structures developed in the mafic volcanic sequence to the northwest of the McDermott shear zone.


In addition, there remains excellent potential to add to the current mineral resource base immediately adjacent to the Holt deposits that can be accessed from the present underground workings. This includes, but is not limited, to the following areas:

• Down plunge and up-dip extension of Zone 4;

• Westwards along the hinge line formed by the known deposits within the Holt mine where additional zones of mineralization may exist; 


Source: http://www.sasgoldmines.com/s/Holt.asp