There is on the record another Certificate in the form of a letter, dated February 3, 1965, from the Director, National Metallurgical B Laboratory, Jamshedpur, addressed to the Controller of Customs, Calcutta, in which it is opined : "The wolfram ore is always selectively mined in the technical terminology .... such "selective mining" does not constitute a manufacturing process. Unless selective mining is done, the tungsten ore cannot be exported or even sold in the country of its origin. In view of the above, the import of selectively c mined tungsten ore containing 65% W03 or more should not be __ regarded as the import of a product which has been manufactured'_ overseas and has passed through the manufacturing process. By the __,expression 'selecti'.'ely mined', we mean that the wolfram ore is detached and taken out from the rock in which it is embedded '1nd 0 this is done by crushing the rock and sorting out piece of wolfram ore therefrom either by hand or by washing or magnetic separa- tion." Then, there is another Certificate from R. Y. Briggs & Co. Pvt. Ltd., who claim to have been analysing various ores and minerals E including wolframite for over 60 years. According to these experts, wolframite is always concentrated as part of the mining operation. The normal method is by washing the crushed ore, thereby freeing the mineral from the gangue. These experts have further certified that the wolfram ore, which they have analysed for M/s. India Hard F Metals, is processed except for physical concentration by washing. It may be observed that in the Minerals & Metal Trading Corporation (ibid), also, this Court had relied upon a similar Certificate from R. V. Briggs & Co. Still, another Certificate, dated January 13, 1965, which is more or less to the same effect as the Certificate of the National Metallurgical G Laboratory, was brought in evidence. A similar Certificate from this Laboratory was relied upon as authentic expert opinion in the earlier case, also, decided by this Court. No authority or expert -0pinion has been cited before us that a concentration of 75 per cent tungsten in wolframite ore of commercial H quality, cannot be achieved merely by 'selective mining', i.e. the physical process of crushing, washing, gravitation, magnetic separation or the like. Nor is there any evidence on the record to show
