Page images
PDF
EPUB

679, U. S. Geol. Surv., p. 257, 1921] for richterite. Tirodite also shows a higher 2V and extinction than for cummingtonite as quoted by Larsen (p. 257).

Tirodite is obviously of metamorphic origin.

Quarterly Statistics of Production of Coal, Gold and Petroleum in India including Burma: January to March 1938.

Coal.

[merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

J. A. DUNN.

P. C. Roy.

7,394

5,440

4,070

8,009

[blocks in formation]

TOTAL

27,099

24,913

26,841

78,853

[merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

*These figures represent the total amounts of gasolene derived from natural gas at the well-head. Of these amounts a portion is sold locally as 'petrol' and the remainder is mixed with the crude petroleum and sent to the refineries. The figures given in the two columns, therefore, together represent the total raw products' obtained. These remarks apply to the similar totals quoted in previous Records.

A. M. HERON.

Bismuthinite and bismutosphaerite from Manbhum.

(With Plate 19.)

Recently a number of specimens of barytes were submitted to the Geological Survey of India for identification from near Malthole village (23°26′; 86°26′) in Manbhum district. Dr. A. L. Coulson has mentioned the occurrence of barytes at this particular locality in Memoir LXIV, Part I, p. 93 (1933).

Several of the specimens contained galena and bismuthinite. The latter mineral has not previously been recorded from the Indian Peninsula, although bismuth has been recorded by Ball as occurring in traces in the Singhbhum copper ores.

Under the reflecting microscope the bismuthinite is seen to be finely intergrown with galena (Pl. 19, fig. 1). In places cerussite and bismutosphaerite pseudomorphically replace the galena and bismuthinite (Pl. 19, fig. 2). The exact relation between the sulphides and barytes is not clear. The two minerals were identified on the following properties:

Bismuthinite. Polishes readily like galena. Hardness: B, less than galena. Reflectivity: about 50, higher than galena. Colour: white, with yellowish tint. Anisotropism: strong, showing yellow, blue, green and grey colours.

Etch tests: Negative KCN, KOH, HgCl2, FeCl3, HCl.
Positive-HNO3 with effervescence.

Microchemical tests: Bi and S present. No Pb.

Bismutosphaerite.-Polishes readily. Hardness: B†, a little greater than cerussite. Reflectivity: 8. Colour: grey. Anisotropism: masked by the vivid yellow internal reflection. Etch tests: Negative-HgCl2, KOH, KCN.

Positive-FeCl3, effervesces with dilute HCl and

HNO3.
Microchemical tests: Bi, no Pb.

EXPLANATION OF PLATE 19.

FIG. 1.-Intergrowth of bismuthinite and galena. Crossed nicols. FIG. 2.--Bismutosphaerite (dark grey) and cerussite (light grey). (white). P. S. 217. X 54.

P. S. 217. X54.
Unreplaced galena

J. A. DUNN.

Apatite and allanite in barytes from Manbhum.

Amongst specimens of barytes from Malthole village, Manbhum district, were several containing crystals of apatite. This association of apatite with barytes is rather interesting, as no such association has been recorded previously, hence this note. The barytes in which the apatite occurs is a fresh white crystalline compact tabular variety. The apatite is sea-green in colour and is either transparent or translucent. The crystals are prismatic, with well developed faces. The specific gravity of the separated crystals is 3-19 and the mean refractive index of the crushed material 1-630-002. It is a fluor-apatite. Under the microscope the crystals are seen to be often rather crushed. The apatite is fairly abundantly disseminated throughout the barytes and occasional segregations give the specimen a greenish colour in places. Occasionally their linear arrangement gives a banded appearance to

the specimen. The apatite, generally, appears to have crystallised prior to the barytes, but the inclusion of barytes in apatite was noticed in one instance.

It may be interesting to note that the apatite is more abundant where barytes is the only other mineral, and is either scarce or entirely absent where galena is present in large quantities. The association of apatite in barytes would probably throw some light on the origin of the barytes in this particular locality.

In one specimen the barytes contained well formed platy crystals of allanite of a deep brownish red colour, which again is an unusual mineral association.

J. A. DUNN and V. B. RAO.

MGIPC-M-VIII-1-9-11-1-39-800.

« PreviousContinue »