Altavista moves Santa Anna to feasibility — Geologists struggle to decipher pattern of gold mineralization

Step by step at its Santa Anna property, Montreal-based Altavista Mines (AIA-) is developing what may become Quebec’s next new gold mine.

The property is situated 15 km west of La Sarre, close to the Ontario border.

Unlike so many of the Abitibi region’s gold deposits, which are formed in shear zones, the Santa Anna deposit is hosted by a granitic pluton, the Manley, which extends about 1.8 km in length and 1.2 km in width. Gold occurs in a coarse and free form in large quartz veins and quartz stockworks.

Altavista holds a full interest in 42 claims covering 1,680 ha and can acquire a 90% interest in 47 contiguous claims covering 1,880 ha.

The deposit was discovered in 1923 and, in subsequent years, two shafts were sunk. However, development ceased when the gold veins were found to be short-lived and erratic. More recently, in 1981, Newmont Mining evaluated three veins at Santa Anna.

Shortly after its initial public offering, two years ago, Altavista began exploring Santa Anna in the hope that the Manley granite would prove as gold-enriched as the Mooshla granite, 80 km to the southeast, where Cambior has built the Mouska gold mine.

Updated resources at Santa Anna in zones 8, 10, 12, 16, 18 and 20 stand at 1.6 million tonnes grading 3.18 grams gold per tonne, for more than 150,000 contained ounces of gold. The figure was calculated using a 2-metre minimum mining width and a cutoff grade of 1.4 grams gold. With a cutoff grade of 3 grams, the resource drops to 600,641 tonnes of 5 grams gold, equivalent to 89,000 contained ounces.

Any production at Santa Anna would begin with the open-pit mining of portions of zones 10, 12, 16, 18 and 20, to be followed by underground mining of portions of those zones plus zone 8. Altavista is in the process of developing mine plans as it begins a feasibility study.

As part of that study, Altavista will drill about 10,000 metres of core: the first 4,000 metres are intended to elevate more of the resource into the proven and probable categories, while the final 6,000 metres will test for possible extensions of the 8 and 10 zones, which together account for more than half of the 150,000-oz. resource and remain open laterally and at depth.

Zone 8, discovered last autumn, extends over 500 metres and to a depth of at least 150 metres. It is characterized by a reddish alteration with an average width of 6 metres.

Zone 10, discovered early this year, lies 100 metres east of zone 8 and is characterized by strong silica and carbonate alteration. It is more than 400 metres long and up to 80 metres wide.

A significant part of Santa Anna’s gold mineralization occurs within granite-hosted quartz veins at the margins of ultramafic (peridotitic) blocks contained within the pluton. One of the key objectives of the drilling is to delineate further the size, shape and orientation of these blocks.

Explains Altavista geologist Marc Legault: “It comes down to the differing competency of the ultramafic blocks, compared with the granitic host rock.

In reaction to stress, the softer blocks deformed without fracturing while the host rock fractured around the margins of the blocks, allowing vein gold to be deposited at the ultramafic-granite contacts.”

The company’s geologists need to refine their understanding of where and how gold becomes concentrated at the block margins, as no clear pattern has yet emerged. Until that problem is overcome, the company will have to continue being conservative in its resource estimation.

A 5,000-tonne, surface bulk sample taken at Santa Anna in 1995 graded 2.5 grams per tonne with a 95.3% recovery, but management feels that unnecessary dilution has rendered the value of the grade deceptively low. New bulk-sampling and metallurgical tests will be conducted as part of the feasibility study.

Altavista President Guy Hbert says that once the geological problems are sorted out, the remaining hurdle will be negotiating milling arrangements for the Santa Anna ore.

Milling options

Apart from the option of constructing its own mill, Altavista knows of at least three mills in the area that are hungry for feed, including Cambior’s (CBJ-T) Vezina mill in Destor, Que., which will be idle following the suspension of operations at Battle Mountain Gold (BMG-N), and Cambior’s Silidor gold operation, west of Rouyn-Noranda.

Referring to dealing with Cambior for its mill, Hbert says, “It’s a poker game right now — we don’t need them and they don’t need us.” Hbert, after whom Cambior’s Bouchard-Hbert polymetallic mine in northwestern Quebec is partly named, is also president of Lyon Lake Mines (LLL-M), which is achieving producer status with its new Beta Vargas gold mine coming on-stream in Costa Rica.

Altavista’s other main projects include the Montbray, Lost Bay and Quenonisca gold properties in northwestern Quebec, as well the Wild Mick gold prospect in Zimbabwe. The company can acquire a half interest in Wild Mick from Inmet Mining (IMN-T).

Altavista is involved in the Sept-les base metal play, with two properties — Chiskal and La Source — comprising 383 mining claims near Soquem’s nickel-copper discovery.

Last month, Altavista completed a private placement of 591,000 shares at $1.10 for a total of $650,000, most of which will be applied to exploration of the two Sept-les prospects. Upcoming work includes cartography, prospecting and a stream-sediment geochemical survey.