The November 1989 issue of Mining Magazine carried the following article on page 353:

Gold at Tyndrum

 

 

 The quest for gold during the current worldwide exploration boom has extended to most 

parts of the globe and Scotland has proved no exception.  A number of companies are 

currently active and have been encouraged in no small measure by the success of  Dublin-based 

Ennex International plc. Currently thwarted by the inability to use conventional drill and blast 

methods to exploit its substantial underground gold reserve at Curraghinalt in the Sperrin 

Mountains of Northern Ireland because of security considerations, Ennex is now concentrating 

its efforts in the British Isles on the development of its Cononish gold property in the Scottish 

Highlands near the old lean mining district centred on Tyndrum.  It has outlined a mineable gold 

resource of some 0.9 Mt grading around 10 g/y and, subject to favourable metallurgical testwork, 

final feasibility and permitting, production could start by the end of next year.

            There are historic records of gold occurrences at a number of Scottish localities dating 

back to the thirteenth century but gold has never been mined on a significant scale.  Exploitation 

has been limited to alluvial operations in the far north in Sutherland and the leadhills district of 

Lanarkshire in the south.  Of the few recorded gold occurrences in the Highlands the more 

significant have been in the headwaters of the River Tay, near Tyndrum.

            Lead mining at Tyndrum began in the mid-eighteenth century and continued intermittently 

until 1858 by which time several thousand tonnes of lead ore had been recovered at grades 

believed to be of the order of 5-10% Pb.  The veins had been mined through a vertical interval 

of 230 m and the last attempt to re-open the mines was in the early 1920s.

            Ennex's Cononish gold property is located about 3 km southeast of the village of Tyndrum 

at the site of the Eas Anie lead mine which exploited a southwesterly striking vein structure accessed 

by two adits driven into a cliff-face.  In 1984 rock sampling near the adit portals and subsequent 

trenching over the adjacent hill-top showed the presence of gold and spurred Ennex to launch a 

10-hole drilling programme at the end of 1985 southwest along the strike of the lead vein structure.  

Gold was encountered in all holes down to a depth of 50 m but, with the exception of two holes, 

values were disappointing.

         Following a review of all exploration data an intensive exploration programme was relaunched 

in 1987 and drilling was stepped back to test the lateral extent of the earlier drilling intersections.  

This rapidly led to the discovery of an auriferous quartz-sulphide structure running parallel to, but a 

few metres north of the main Eas Anie lode.  The goldbearing structure, which is hosted by a 

succession of Dairadian psammites and pelites, was traced westwards over a strike distance of 

700 m with gold intersected in 35 of the 55 holes drilled.  Gold grades improved along the strike 

with intercepts of up to 13.5 m at 29.14 g/t in the westernmost section.  No hole has been drilled 

deeper than 300 m vertical depth and mineralization remains open at depth.

            By the end of 1987 Ennex had secured exploration licences with mining lease options over 100 

km2 .  A planning application was submitted for an underground operation programme of drifting and 

raising, the objective being to validate the ore reserve estimates above the adit level and provide data 

necessary for the full-scale feasibility study.  Work on the adit began in September 1988 and is progressing 

at the rate of 20-30 m/week.  To date it has reached 700 m and its planned length of 900 m will be 

completed by the end of 1989.  Originally it was intended to extend the 'old man's' adit along the structure 

on the 448 m level but a decision was made to step back 200 m east and drive a new adit on the 400 m 

level.  Although this has meant driving through several hundred metres of barren ground initially, the surface 

drilling had indicated that the gold structure plunges west so that locating the adit at a lower level gives 

access to 0.2 Mt more ore than would have been the case otherwise.

            Thus far the underground exploration has borne out the surface drilling, confirming the continuity 

of grade and structure.  The structure averages 1.65 in width in the section developed to date and the 

richest ore is concentrated along a well-defined hanging wall in the psammite.  Grades diminish away 

from the hanging wall and tail off in a brecciated zone which forms an ill-defined footwall.  Mineralization 

tends to favour the psammite rather than the pelite horizons because the former are more competent and 

the fracturing more open.  Warp structures also give rise to thicker zones and better grades.

            Close to the hanging-wall the gold is sometimes visible but for ore reserve calculation purposes, 

where individual assay values exceed 60 g/t they have been cut to 60 g/t and values between 30 g and 

60 g have been cut to 30 g/t.  Gold occurs as 5 to 100 micron-sized grains, chiefly intergrown with 

galena contained in microfractures in pyrite grains.  Wallrock alteration includes chloritization, sericitization 

and haematization.  A later episode of more widespread non-auriferous quartz-carbonate-sulphide veining 

forms the basis of the historical lead mining.  Both appear to be shearzones associated with the main regional 

control, the Glen Fyne fault.

            Bulk samples have been sent to Canada for metallurigcal test-work and at this stage flotation seems 

to be the most favoured route for ore treatment.  For a 125,000 t/y operation an appropriate processing 

facility would cost an estimated E3.5 million with the total capital cost of the project likely to be of the order 

of  E7 million.  Mining costs should be less than E30/t and total operating cash costs, not including financing 

charges, around $ 230/oz.

            The location of the mine in an area of outstanding natural beauty means that great care will need to 

be taken to ensure that tailings disposal, ore treatment methods and plant installations have minimal impact 

on the environment.  Consultants W. J. Cairns of Edinburgh have been engaged to undertake environmental 

base-line studies and an environmental impact statement will be submitted to the planning authorities by the 

end of the year.  Cononish could employ as many as 100 people of whom half would be drawn from the 

local communities.  there seems no good reason why mining, as well as forestry and tourism, should not make 

a modest but valuable contribution to the Highlands economy.



Tony Brewis