Bigstone

Location and Infrastructure

Foran’s 16,117 hectare Bigstone Property is located in east central Saskatchewan, approximately 85 km west of Flin Flon, Manitoba. Provincial highway 106 and transmission lines cross the northern end of the property.

The Bigstone deposit, in the southern part of the Bigstone property, is accessible via helicopter, boat or winter road. Winter road access is 103 km from Flin Flon along Saskatchewan Provincial Highway 106 and 17 km south on a winter access trail. The Bigstone deposit lies approximately 25 kilometres west of Foran’s McIlvenna Bay deposit and is accessible in winter from Foran's Hanson Lake exploration camp via a 51 km gravel road, highway 106 and winter roads.

The mining town of Flin Flon (pop. 5,600), is the largest commercial/residential centre in the area and a railhead on the Hudson Bay railway. The Flin Flon airport has regular commercial air service to Winnipeg.

Ownership

Foran owns a 100% interest in the Bigstone Property. Some of the claims that make up the property are subject to a 2% NSR.

History and Past Work

The electromagnetic conductor associated with the Bigstone deposit was first identified by a 1963 Selco airborne geophysical survey. The Bigstone deposit was subsequently discovered by drilling in 1982 by a Granges Inc./SMDC (Cameco) joint venture. The Granges/SMDC (Cameco) JV continued exporation at the Bigstone deposit and on regional targets elsewhere on the property until 1994. Several historic mineral resources have been prepared for the Bigstone deposit; the most recent was prepared by Cameco in 1990 (see below for the historic mineral resource and important disclosures).

In 1995, Granges Inc. interest in the JV was purchased by Aur Resources Ltd. Aur operated several exploration programs on the property until 2002 when the project was shelved.

In 2003, Foran purchased Aur Resources interest in the project. Foran commissioned a high-resolution VTEM Time Domain Electromagnetic ("EM") survey over portions of the property in 2007. In 2011 Foran completed additional VTEM surveying over ground not covered by the 2007 survey. The two datasets were then merged and interpreted by an independent geophysical consultant to identify exploration targets.

Early in 2012, Foran purchased Cameco's remaining interest in the project, becoming 100% owner and subsequently in the spring of 2012, Foran drilled four holes (1,176 metres) to test three north-south oriented VTEM conductor trends in the northern part of the property, in an area known as the Freeport Zone. For additional information on this drilling see the Foran news release dated July 9, 2012.

In 2014, Foran conducted a ground-based EM geophysical survey over the Bigstone deposit area to better resolve the conductor associated with the historic deposit and other nearby conductors.

In winter 2015, Foran conducted infill drilling on the Bigstone deposit 1. For additional information on this drilling see below and the Foran news release dated May 20, 2015.

Regional Geology

The Bigstone deposit is located at the western limit of the Paleoproterozoic Flin Flon Greenstone Belt (FFGB) which extends from east-central Manitoba west into Saskatchewan. The FFGB forms part of the Reindeer Zone, a subdivision of the Trans-Hudson Orogen, a continental-scale tectonic event which occurred approximately between 1.84 Ga and 1.80 Ga as a result of the collision between the Superior and Hearne Archean Cratons.

The Bigstone deposit occurs under flat-lying Phanerozoic cover within upright volcano-plutonic and related sedimentary rocks of the Northern Lights Assemblage (NLA), the western most of two tectonostratigraphic assemblages cumulatively referred to as the Hanson Lake volcanic belt. The adjacent Hanson Lake Assemblage (HLA) is host to Foran’s McIlvenna Bay Cu-Zn-Au-Ag deposit located 25 kilometres east of Bigstone.

Deposit Geology

The Bigstone deposit is hosted within an intensely altered and metamorphosed volcanic sequence dominated by andesite to dacite tuffs with footwall quartz +/- feldspar porphyries and hangingwall rhyolite tuffs and graphitic argillite beds. The stratigraphy in the deposit area is north trending, west facing and upright to steeply west dipping. Rocks have been subjected to amphibolite facies regional metamorphism.

The principal sulphide body at Bigstone is the Main Zone which occurs as a vertical to steeply south plunging, flattened cylinder up to 60 metres thick with a strike length of 150 metres and drill tested from 100 to 700 metres below surface. The Main Zone is stratigraphically overlain and overlapped to the south by a high-grade Zn-rich massive sulphide horizon measuring roughly 200 by 400 metres in size with intersections up to 10 metres thick.

The main zone consists of two styles of mineralization: the Main Zone (Copper) and Main Zone (Zinc) horizons. These mineralized horizons are associated with intense hydrothermal alteration which is texturally destructive making the identification of primary lithologies difficult. Rocks in the Main Zone (Copper) lenses tend to be associated with an iron-rich alteration assemblage consisting of chlorite, chloritoid, magnetite and garnet (+/- silica). Mineralization is characterized by coarse disseminated to semi-massive and locally vein styles of pyrrhotite, chalcopyrite, magnetite and lesser pyrite and arsenopyrite (+/- sphalerite). Transitional to the iron-rich alteration is a strong silica-sericite alteration assemblage which is generally associated with an increase in the zinc content. This style of alteration hosts the Main Zone (Zinc) horizons which are generally located peripheral to the copper-rich zones and are characterized by stringer-style red sphalerite (+/- gahnite), pyrrhotite and pyrite (+/- chalcopyrite) mineralization.

The massive sulphide horizon generally consists of massive to semi-massive coarse grained red sphalerite mineralization with laminated pyrrhotite (+/- local minor galena and sulphosalts). The horizon is laterally extensive, but variable in thickness (from <1m to +10m) and generally occurs 5-20m stratigraphically above the Main Zone. The horizon is host to high grade zinc mineralization, with individual assays of >40% zinc returned locally from 2015 drill core sampling.

Exploration

Foran's winter 2015 program at Bigstone included six infill diamond drill holes (2,545m) into the historic Bigstone resource 1. The program tested the central parts of the deposit at depths of 200 to 350m below surface.

The Bigstone historic resource is a vertically oriented, flattened, cylindrical shaped body, in part drill tested between 100 and 700m below surface.

Highlights from the winter 2015 Drill program include:

  • 2.0% Cu over 105.0m, including 4.1% Cu over 20.4m and 3.2% Cu over 19.0m in BS-15-239
  • 18.4% Zn over 11.8m (including 27.0% Zn over 7.6m), followed further downhole by 1.42 Cu over 10.6m and 1.3% Cu over 8.5m in BS-15-240; the first two of these intercepts are within an approximately 95m thickness of massive to semi-massive, stringer, and disseminated sulphides; intervals within the zinc zone grade up to 41.7% Zn over 1.0m.
  • 2.5% Cu over 53.6m (including 4.0% Cu over 12.3m) in BS-15-242,
  • 2.5% Cu over 58.0m (including 3.8% Cu over 15.3m) and 11.2% Zn over 3.0m in BS-15-243, and 15.1% Zn and 778 g/t Ag over 4.8m (including 32.4% Zn and 2,322 g/t Ag over 1.6m), followed further downhole by 1.2% Cu and 7.8% Zn over 29.0m in BS-15-244.

True thickness is interpreted to be approximately 50-60% of drill indicated. For additional information see the Foran news release dated May 20, 2015.

Mineral Resources

In 1990, Cameco outlined an historic mineral resource * at the Bigstone deposit with an estimated 3.75Mt grading 2.03% Cu and 0.33 g/t Au at a 1% Cu cutoff in the Main Zone and an estimated 0.53Mt grading 9.62% Zn and 15.9 g/t Ag at a 5% Zn cutoff in the Zinc-rich Massive Sulphides.

Bigstone deposit Main Zone historic resource estimate sensitivity analysis 1

Cu cut-off (%Cu) Tonnage Cu (%) Zn (%) Au (g/t) Ag (g/t)
1.0
1.5
2.0
2.5
3,747,500
3,136,600
1,983,600
1,199,300
2.03
2.26
2.57
3.11
0.14
0.15
0.17
0.20
0.33
0.36
0.48
0.61
9.3
9.9
11.3
13.5


Bigstone deposit Massive Sulphide Zone historic resource estimate sensitivity analysis 
1

Zn cut-off (%Zn) Tonnage Cu (%) Zn (%) Au (g/t) Ag (g/t)
2.0
3.0
4.0
5.0
755,200
692,600
611,500
525,300
0.20
0.21
0.21
0.24
7.75
8.22
8.87
9.62
0.27
0.28
0.30
0.34
11.7
12.6
13.9
15.9


1Foran is not treating the historic estimate as current; a Qualified Person within the meaning of National Instrument 43-101 has not completed sufficient work to classify the historic estimates as current; additional work, including re-surveying, re-logging and drill core QA/QC would be required to verify and upgrade the historic estimate to current.

Metallurgy

On November 17, 2015 Foran released the results of positive initial metallurgical testwork for Bigstone.

Testwork was conducted on composite drill core samples (quartered HQ core) from each of the three main styles of mineralization at Bigstone, namely the Main Zone (Copper), Main Zone (Zinc) and Massive Sulphides (Zinc). The Main Zone (Copper) is the most significant of the three styles of mineralization. The program was designed to test the recovery characteristics of the three composites utilizing conventional flotation methods followed by locked cycle tests to produce copper and zinc concentrates. All styles of mineralization produced high-grade concentrates with good recoveries.

Highlights included:

  • Recoveries of 93% Cu, 52% Au and 82% Ag to a copper concentrate grading 29.2% Cu, 1.9 g/t Au and 118 g/t Ag from the Main Zone (Copper),
  • Recovery of 90% Zn to a zinc concentrate grading 55.3% Zn and recoveries of 43% Cu, 48% Au and 38% Ag to a copper concentrate grading 29.4% Cu, 7.7g/t Au and 238 g/t Ag from the Main Zone (Zinc),
  • Recoveries of 90% Zn and 73% Ag to a zinc concentrate grading 54.1% Zn and 471g/t Ag from the Massive Sulphides (Zinc),
  • Mineralization is amenable to conventional flotation processes to recover the base and precious metals to saleable concentrates, and
  • Grindability testwork indicates moderate hardness for the three styles of mineralization.

Overall Metallurgical Response

Main Zone (Copper)

Product

Mass

Concentrate Grade

Recovery

Cu

Zn

Ag

Au

Cu

Zn

Ag

Au

(%)

(%)

(%)

(g/t)

(g/t)

(%)

(%)

(%)

(%)

Feed

100

1.85

0.10

9

0.21

100

100

100

100

Copper Concentrate

5.9

29.2

0.59

118

1.8

93

35

82

52

Main Zone (Zinc)

Product

Mass

Concentrate Grade

Recovery

Cu

Zn

Ag

Au

Cu

Zn

Ag

Au

(%)

(%)

(%)

(g/t)

(g/t)

(%)

(%)

(%)

(%)

Feed

100

0.70

5.22

6

0.16

100

100

100

100

Copper Concentrate

1.0

29.4

2.32

238

7.7

43

0

38

48

Zinc Concentrate

8.5

3.06

55.3

24

0.32

37

90

32

17

Massive Sulphides (Zinc)

Product

Mass

Concentrate Grade

Recovery

Cu

Zn

Ag

Au

Cu

Zn

Ag

Au

(%)

(%)

(%)

(g/t)

(g/t)

(%)

(%)

(%)

(%)

Feed

100

0.24

10.1

108

0.29

100

100

100

100

Zinc Concentrate

16.8

0.99

54.1

471

1.1

70

90

73

65

Bond Work Indices

Composite

Bond Rod Mill Grindability Test

Bond Ball Mill Grindability Test

Abrasion

Work Index (kWh/tonne)

Work Index (kWh/tonne)

(g)

Main Zone (Copper)

15.9

13.5

0.494

Main Zone (Zinc)

14.9

12.5

0.481

Massive Sulphides (Zinc)

14.2

11.1

0.381

A total of 560 kilograms of material was shipped to Base Metallurgical Laboratories Ltd. (“Base Met Labs”) in Kamloops, B.C. for processing. The nominal primary grind size was 100µm K80, with target regrind sizes for the concentrates of 30 to 40µm K80.

Main Zone (Copper)

The Main Zone (Copper) composite was dominated by copper mineralization with very little zinc. Flotation testing focused on production of a gold- and silver-bearing copper concentrate. Optimization of the process was limited to testing various primary grind sizes, collector types and the effect of regrind sizes. Flotation response was very robust, allowing for the use of low-cost collectors (xanthate) and simple pH modulation of the flotation circuit to control pyrite and other unwanted sulphides.

Main Zone (Zinc)

The Main Zone (Zinc) feed had copper and zinc concentrations that required production of separate concentrates. The copper concentration in the feed was considerably lower than the zinc. Limited optimization was conducted on this sample, focused on controlling zinc recovery to the copper concentrate and producing high grade zinc concentrates.

The initial results were very encouraging, demonstrating very good zinc flotation performance. The copper circuit produced a high-grade copper concentrate, with lower recoveries. This style of mineralization would benefit from further optimization testing focusing reagent and regrind optimization in the copper and zinc.

Massive Sulphides (Zinc)

The Massive Sulphide (Zinc) composite had a high zinc concentration, with relatively low levels of copper; the sample contained abundant iron sulphides.

Flotation testing was focused on production of only a zinc concentrate from this mineralization. Batch testing investigated the effect of regrind on the rougher concentrate and effect of elevated pH in the cleaner circuit. The test results indicated that elevated pH levels and the use of more selective collectors were beneficial (Dithiophosphates), resulting in the production of higher grade zinc concentrates.

Bond Work Indices

Bond rod mill work index determinations for the composites ranged from 14.2 kWh/tonne to 15.9 kWh/tonne, with an average of 15.0 kWh/tonne. Bond ball mill work index determinations for the composites ranged from 11.1 kWh/tonne to 13.5 kWh/tonne, with an average of 12.4 kWh/tonne. Based on these results the mineralization would be considered to have a moderate hardness from a rod and ball milling perspective.

Page Last Updated: Feb 09, 2016