Danie Krige – an international household name to anyone who studied or practised the science of evaluating mineral resources for mining purposes – died recently in Johannesburg.

While his name may not be familiar to many people outside the field, so new and revolutionary were his ideas – applying mathe- matical statistics to the spatial evaluation of orebodies – that the processes he developed were named after him, becoming known in the industry as ‘kriging’. This technique has helped improve ore evaluation techniques and reduce the financial risk of investing in mining projects.

The significance of his work to the global mining industry is difficult to overestimate; over the years, his work was recognised by such institutions as Moscow State Mining University, which awarded him an honorary doctorate, and the US National Academy of Engineering, where he was the first South African ever to be elected a foreign associate in earth resources engineering.

Back home in South Africa, his doctorate, in engineering, awarded by the University of the Witwatersrand (Wits), was augmented by three honorary doctorates – from Pretoria University, the University of South Africa and his alma mater.
As recently as last year, he received the Order of the Baobab (Silver) from the South African President for exceptional and distinguished contributions in business and the economy, science, medicine and technologi- cal innovation and community service. The only other mining person to have received this award is African National Congress deputy president Cyril Ramaphosa, for his contribution during the democratic transformation negotiations.

Through his career, Krige received several awards from bodies like the South African Institute of Mining and Metallurgy, the US’s Society for Mining, Metallurgy and Exploration, the South African Academy for Science and Arts, the International Association for Mathematical Geology, the International APCOM Council (Application of Computers and Operations Research in the Mineral Industry) and the University of Antofagasta, in Chile.

Born Daniel Gerhardus Krige in Bothaville, in the Free State, in 1919, he matriculated at the age of just 15 from Monument High School, in Krugersdorp. By the age of 19, he had graduated from Wits with a bachelor’s degree in mining engineering.

He began his career at Anglo Transvaal (later Anglovaal) in 1938, where he cut his teeth on a number of gold mines, doing surveying, sampling and ore valuation. In 1943, he joined the Government Mining Engineer’s (GME’s) depart- ment, where his work included designing the uranium pricing formula for negotiation with British and American authorities. This laid the groundwork for South Africa to develop a profitable uranium industry in the early 1950s.

It was during this time – when he was barely 30 years old – that he began his pioneering work on applying insights in statistics to the valuation of new gold mines, using a limited number of boreholes. Part of his work at the GME’s department involved granting mining leases for gold mines, but he was concerned that deep gold mines were being established on the basis of very few boreholes and without proper scientific analysis of this scant data. The situation posed very high risks to profitability, but there seemed to be no real alternative.

Building on the work of fellow statistician Herbert Sichel, Krige started applying statistics to the data, eventually developing a logi- cal and scientifically based procedure for evaluating the scarce information gleaned from borehole drilling. This was applied not only to new mines but also to ore reserve calculations for existing operations and earned him his master’s degree in mining engineering – also from Wits.

In a seminal 1951 paper published in the Journal of the Chemical, Metallurgical and Mining Society of South Africa, he pursued a statistical explanation of the conditional biases in ore block valuations – the basis for the practice of kriging.
Krige returned to Anglovaal as group financial engineer in 1951, and was responsible for ore evaluation, mine surveying, financial analyses of mining projects, share valuations and technical computing facilities. During the early 1960s, he implemented geostatistical kriging procedures on Anglovaal’s two large gold mines. This was the first routine application of the kriging of ore reserves in the world.

There was particular interest in his ideas from France after some of his papers were translated into French in 1955, eventually resulting in the creation of the famous research centre for ore evaluation in Fontainebleau, Le Centre de Geostatistique de l’École des Mines de Paris.

He retired from the private sector in 1981, taking up the post of Professor of Mineral Economics at the School of Mining Engineer- ing at Wits, where he gave mainly postgraduate courses in geostatistics and mining economics and supervised many master’s and doctoral theses. He remained with the university until 1991. His research continued unabated – especially into practical applications of geostatistics in ore evaluation – leading to his publication of some 90 technical papers worldwide over the course of his career.

Even after his retirement from academia, he continued under- taking research, lecturing and publications, and consulted in resource/reserve valuation and financial analysis for several local and global mining companies.