JUDGMENT

BHARUCHA, J.- The appellants (original writ petitioners) import asbestos fibre and pay customs duty thereon under Entry 25.01.32, which reads:

"Mineral substances, not elsewhere specified ... :

(1) * * *

(2) Asbestos raw including fibre 40%

(2) * * *

There is no dispute in regard to the levy of customs duty. The dispute is in regard to the levy on the imported asbestos fibre of additional duty under Section 3(1) of the Customs Tariff Act, 1975, which is quoted hereinafter. The appellant in Civil Appeal No. 1354 of 1980 also mines asbestos in India and is made liable to pay excise duty thereon under Tariff Item 22-F, which reads thus:

________________________________________________________________________

"Item

No.

Description of goods

Rate of Duty

________________________________________________________________________

22-F

Mineral Fibres and yarn, and

manufactures therefrom in or in relation to the manufacture of which any process is ordinarily carried on with the aid of power.

Fifteen per cent ad

valorem

Explanation : Mineral fibres and yarn, and manufactures therefrom shall be deemed to include :

(i) glass fibre and yarn including

glass tissues and glasswool;

(ii) asbestos fibre and yarn;

(iii) any other mineral fibre or yarn,

whether continuous or otherwise

such as slagwool and rock wool;

and

(iv) manufactures containing other

than asbestos cement products."

This levy is also disputed. By the common judgment under appeal, the Delhi High Court dismissed the writ petitions.

2. The constitutionality of the imposition of excise duty on asbestos fibre is not now disputed.

3. What asbestos is and how it is recovered is set out in the judgment under appeal, and it is not faulted on this account. This is what it says:

"Major producers of asbestos are Canada and USSR. Asbestos is defined as general name for the useful fibrous varieties of a number of rock forming minerals. The value of asbestos ensues from the incombustible nature of the products fabricated from the various grades of mineral fibres. [Vide McGraw Hills Encyclopaedia of Science and Technology, Vol. 1 (1977), p. 618.] Most asbestos fibres occur in small cracks in massive rocks and are difficult to recover e.g. a large cubic open pit mine handles approximately 16 tons of ore. 8 tons of waste ore and 23 tons of overburden to produce a single ton of asbestos. To mine chrysotile, the ore is first blasted loose. The larger asbestos seams i.e. those that are at least 9.5 mm wide are picked from the ore after blasting and adhering rock is removed with a pick. The resulting chunks of ore called crudes, which may contain as much as 30% water, are then dried in preparation for the next stage - separation into fibres. Fibre separation is accomplished mainly by a series of shaking screens, special separators called cyclones, and additional crushers or fibrizers. At each shaking screen the liberated fibres are sucked off by an airstream and collected for grading and packaging. The larger pieces of ore, which are retained by the screen are recycled for further crushing. Smaller pieces, which pass through the screen and are called throughs, are sent to the next crushing or fiberizing sequence. The extremely small pieces that fall through the screens following the final fiberizer are discarded. [Vide Encyclopaedia Americana, Vol. II (1970), pp. 427, 428.]

Similarly the Encyclopaedia of Natural Chemical Analysis, Vol. II gives the processing of asbestos fibre as follows:

Asbestos fibre is recovered by open pit or underground mining operations. In the open pit operation, the ore is taken from the top of the deposit and in underground method, the ore is removed from the bottom of the deposit. One imported method used in underground mining is known as block carving. In this method, a large block of ore is loosened in such a way that it breaks down from its own weight. The ore is extracted through a network of tunnels and carried to primary crushers which break up the large rock chunks into fra