Dia Met Minerals and Ashton Mining Announce Mauritanian Exploration Joint Venture.

KELOWNA, BRITISH COLUMBIA--(BUSINESS WIRE)--May 3, 1999--

Dia Met Minerals(TSE:DMM.A.) (AMEX:DMM.A) (TSE:DMM.B.) (AMEX:DMM.B) Dia Met Minerals Ltd. and Ashton Mining Limited are pleased to announce the formation of a joint venture to discover and develop diamond deposits in the west African country of Mauritania. This region contains the extensive Archaean Reguibat Shield, believed to have excellent potential for the discovery of kimberlitic diamond deposits. Last year, Ashton discovered the country's first kimberlites and diamonds.

The Joint Venture, between Dia Met Minerals (Africa) Ltd., a wholly-owned subsidiary of Dia Met Minerals Ltd. of Canada, and Ashton West Africa Pty Limited, a wholly-owned subsidiary of Ashton Mining Limited of Australia, includes some 214,000 square kilometres (53 million acres) of diamond exploration permits. A further 20,000 square kilometres are under application.

Dia Met's President and Chief Executive Officer, Mr. James Eccott, said: "The two companies have been involved in a collaborative exploration venture in Finland for over a year. With the Mauritania agreement Dia Met and Ashton can exploit their combined strengths and expertise in diamond exploration in virgin Archaean terrain, on a land package larger than the entire Slave craton in Canada. Ashton's work has demonstrated that the project has excellent potential for diamond discovery."

Ashton initiated exploration for diamonds in Mauritania in 1995, and very quickly identified kimberlite indicator minerals with diamond inclusion chemistry in the Reguibat Shield area. Such minerals are commonly associated with significant economic diamond deposits in southern Africa, Canada and Russia, and a number of exploration permits were acquired to cover the most prospective areas.

In subsequent programs Ashton has flown several airborne geophysical surveys in the areas where the most promising indicator mineral results were obtained. Ashton has identified other prospective areas that have also now been secured under licence. In one licence, a kimberlite cluster has been found along

with small diamonds and abundant kimberlite indicator minerals with the sought after diamond inclusion field compositions. In other areas, the spread of indicator minerals, including diamonds,

suggest additional kimberlite clusters remain to be found and work is currently in progress in these areas.

Ashton's Chief Executive Officer, Mr. Doug Bailey, said: "Ashton is very pleased with this new joint venture. It confirms Ashton's strategy of sharing exploration risk and funding with like-minded, high-quality companies such as Dia Met. The joint venture brings together the considerable exploration skills of both companies and provides the financial resources necessary to explore for, discover and evaluate economic diamond deposits in the vast areas covered by this joint venture in one of the last remaining Archaean cratons to be explored for diamond deposits."

Under the terms of the agreement, Dia Met will commit to exploration expenditures of at least US$2.5 million by 31 March 2000, and may acquire up to 49 per cent of Ashton's equity in the project by staged expenditure of up to US$10 million by March 2003. The Mauritanian Government has a 10 per cent equity interest

in some tenements included in the joint venture. Ashton is the operator of the project, but Dia Met will have the controlling vote on programs and budgets as long as Dia Met alone is funding exploration and development.

Dia Met is a publicly traded mineral exploration and development company with a primary focus on diamonds. The company holds a 29 per cent interest in the Ekati Diamond Mine, Canada's first commercial diamond mine, together with BHP Diamonds (51 per cent), Charles Fipke (10 per cent) and Stewart Blusson (10 per cent).

The American Stock Exchange and Toronto Stock Exchange have neither approved nor disapproved the information contained in this release.