Dr Isobel Clark FSAIMM FIMMM CEng


Mine planning and valuation Statistics and geostatistics Software advice and development Environmental issues

underground room and pillar mining


open pit on a mountainside

My consultancy work has been largely in the field of mineral resource and reserve estimation. Most often, my involvement is at feasibility or even pre-feasibility stage. Occasionally it has been possible to indulge my personal preference for working at the grade control stage in a producing mine.

Within this narrow field of specialisation, however, I have gained experience in a wide variety of minerals and mining methods. Whilst the earliest of my activities seem to have been concentrated on base and low-concentration metals, more recent experience has been gained in the evaluation of precious metals. My first contact with coal applications dates back to 1979. Mineralisation types range from stockwork through hydrothermal veins to massive sulphides. Mining methods included in various feasibility studies include back-stoping, cut and fill, open stoping, room and pillar and (of course) open pit block-by-block evaluation.

The organisations for which I carried out work prior to setting up Geostokos Limited include:

Billiton International, The Hague; The Netherlands, British Steel {Overseas Services} Ltd; Charter Consolidated, London; Dept of Industry and Commerce, Dublin, Eire; Geevor Tin Mines Ltd, Pendeen, Cornwall; Geological Survey of Norway; Greenland Geological Survey; Newmont Holdings, Melbourne, Australia; Pancontinental Mining Ltd, Sydney, Australia; Roxby Management Services, Adelaide, South Australia; Shell Coal International, London; Shell South Africa (Metals Division), Johannesburg; Selection Trust Ltd, London later BP Minerals International; Seltrust Engineering, London.

Geostokos Limited was floated on 1st January 1983 as an independent consultancy company serving the Minerals Industry worldwide. The Company is currently managed by two Company Directors: myself and Audun Clark who is a Geomatics specialist.

We offer expertise in the major fields of statistics, geostatistics and computer applications. My official title is Managing Director of Geostokos Limited, which is registered in England and operated out of Central Scotland. It is my responsibility to manage the company, act as senior consulting partner and to manage the employees. We operate with the minimum of permanent staff, drawing on the services of free-lance specialists when the need arises.

It has also been my job to formalise the large body of software available to us into a "Toolkit" for statistical and geostatistical analysis of geological data.

Since setting up Geostokos Limited, our field of activities has widened a little to include hydrogeology, environmental pollution and soil science parameters. In particular, we were involved for four years in the study of a proposed site for a high level nuclear waste repository in the USA. This included detailed study of hydrological characteristics of aquifers in the Texas Panhandle.

Between 1982 and 1989, our clients included:

Battelle Pacific Northwest Laboratories, Richland, Washington; General Mining Union Corporation, Johannesburg; Golder Associates, Maidenhead; Hope Brook Gold, Cornerbrook, Newfoundland; Johannesburg Consolidated Investments Ltd, Johannesburg; Lonrho Plc, London; ONWI, Battelle Memorial Institute, Columbus, Ohio; Steffen Robertson Kirsten, Johannesburg; Terrasciences Inc., Denver, Colorado; Transalta Utilities, Calgary, Alberta

Since 1989 various projects were undertaken, and may be classified as follows:

Mine Planning and Valuation:

Palabora Mine, underground development, RTZ Management Services, Johannesburg.

Stillwater Platinum Mine, Montana; Lisheen Zinc/Lead project, Eire; Collahuasi Copper Mine, Chile; all for Pittsburgh and Midway Coal Mining Company (a division of Chevron USA).

Public statement of remaining reserves at the Droogebult Mine, RSA.

Mine planning assistance at Freda-Rebecca Mine, Zimbabwe for Cluff Minerals (and later Ashanti GoldFields Zimbabwe).

Valuation advice for the Ayanfuri Project, Ghana for Cluff Minerals.

Valuation of Mineral Sands project, California, USA.

Advice on sampling at Richards Bay Minerals, RSA.

Ad hoc advice on mineral sands applications, for Shell Minerals, RSA.

Hartley Platinum, BHP Zimbabwe, peer review.

Fergusson Stewart, Johannesburg, evaluation of Joel Mine.

Potgietersrus Platinum, JCI, benchmark evaluation.

Oryx Mine, Gengold, peer review of estimation methods.

MIMCO, RSA, evaluation of gold mine.

Pancontinental Mining, Western Australia, modelling and evaluation of shear-hosted gold deposits.

Tilden Magnetite, Michigan USA, geostatistical modelling of geological zones and various economic variables.

Stillwater Platinum Mine, Montana USA, grade control problems.

Advice on valuation and sampling procedures for Nelson Gold, Tajikistan.

Investigation of problems with Mine Call Factor for Libanon Mine, RSA.

Evaluation of resources for Wadi Medden Project, Yemen.

Assessment of stockpiles at Norilsk, Osmium, London.

ISCOR Mining, audit of valuation for deposit in Zaire

Lonrho Zimbabwe, advice on evaluation of small gold deposits

American Mineral Fields Int. Ltd., supervision of feasibility study --- valuation and geology

Ghanaian Australian Goldfields, geostatistical modelling and advice on valuation

Blyvooruitzicht Gold Mining Co. Ltd., audit of annual reserve statement

Vaal Reefs Exploration & Mining Co. Ltd., audit of annual reserve statement

Resource Exploration, evaluation of projects in Zaire

MineNet RSA, evaluation of resources and reserves at Skorpion project, Namibia

Tenke Fungurume project, Congo audit of computerised database

Evaluation of mining resources, Hartebeestfontein Mine, RSA

Assessment of Alexander Bay Diamond Mine, RSA

Mineral resource and reserve valuation for Skorpion Zinc project in Namibia.

Study of sampling methods and calibrations for Namco Diamond Mining, Cape Town.

Resource evaluation studies for Lonrho Platinum, South Africa.

Audit of resources, tantalite deposit, Mozambique

Resource evaluation advice, platinum dumps, Norilsk area for a German consortium

Re-evaluation of resource evaluation for South Crofty Mines, Cornwall

Ferguson Lake Ni/Pt project, Nunavut, Canada

 Statistical and Geostatistical Applications

Relationships amongst accident statistics, GenMin, Johannesburg;

Optimal Sampling Intervals, Western Platinum Mine, Lonrho Platinum Division, Rustenburg, RSA;

Investigation of the predictability of seismic events (rockbursts) underground. Hartebeestfontein Mine, RSA.

Duvha coal mine, advice on sampling density.

Shell Coal RSA, advice on sampling density.

Calibration of sampling assays from different laboratories, Bogoso, Ghana.


  Software advice and development

Software development for Lynx Geosystems Modelling System, Vancouver, BC.

Lonrho, Zimbabwe, advice on appropriate software for mine planning.

Micromine, Perth Western Australia, expert advice on development of statistical and geostatistical software.

 Geostokos PC Toolkit:

Educational copies at:

Mackay School of Mines, University of Nevada, Reno

University of the Witwatersrand, RSA

Pretoria University, RSA

Witwatersrand Technicon, RSA

Technicon South Africa, RSA

Auburn University, Alabama

James Cook University, Northern Australia


Environmental Issues

Particulate Emission Levels from Power Stations, ESKOM, RSA --- Majuba, Kendal, Tutuka and Lethabo Power Stations. This work was extended to SO2 and other emissions.

Toxic Waste contamination of groundwater, New Jersey, USA. Rohm & Haas company, Philadelphia.

Pest control for the Citrus Growers of Florida, USA

Assessment of Ra contamination, Idaho, USA for MWH of Seattle

Preservation of Seabirds, particularly in the presence of offshore wind farms: for Joint Nature Conservation Committee (Aberdeen, Scotland) and power utilities in UK

Back to Top of Page Back to Main Resume Page Back to Home Page