06 



MISS C. A. RAISITT 0^ CEKTATK 



[Feb. 1 091, 



with some graphite, biotite, pyrite, and iron-oxide. ISText comes a 

 banded rock, containing tufts of hornblende and of the supposed 

 ottrelite intercrystallized, and abundant graphite. Small garnets 

 begin to occur, and then become more numerous, being especially 

 aggregated at the junction of adjacent bands. The garnets contain 

 inclusions along crystallographic planes^ (see fig. 3, p. 64) ; they are 

 sharp-edged but often imperfect, especially where the lines of inclu- 

 sions start; and they interfere mutually in their growth where a group 

 has formed. Then comes the central banded rock more altered and 

 rather clearer, with some haematite occasionally associated with the 

 tufts, and containing but seldom mineral 'No. 17 (see p. 61), sometimes 

 clinging to a well-formed garnet. The next band contains incipient 

 hornblende or ottrelite, and incipient garnets. These are ill-formed 

 and incomplete, being in places almost entirely occupied by inter- 

 spersed crystalline grains. Then a blacker band containing graphite 

 and incipient hornblende is followed by a greyish band including 



Fig. 4. — Band about 1 foot tJiicJc, containing garnets (often aggre- 

 gated near planes of weaJaiess) and hornblende or ottrelite ; 

 north-east of Basiogne, in quarries along the railway to Gouvy. 



[The rock is markedly stratified, and much jointed.] 



much biotite. In the rock below, greenish films are abundant, opacite 

 is less important, haematite or ilmenite-plates occur, and much 

 biotite. Thus the rock, as we approach the central band, seems to 

 show successively : — (1) minute greenish microliths, small biotite, 

 scattered iron-oxide ; (2) incipient hornblende or ottrelite with 

 graphite ; (3) in addition incipient ill-formed garnets ; (4) hornblende 

 (sometimes with ottrelite) better developed, and well-formed garnets. 

 Another patch of altered rock, seen on a joint-face,^ measures 

 about 18 X 3 inches, is irregularly wedge-shaped, weathering whitish, 



^ See A. Renard, Bull. Mus. Roy. Hist. Nat. Belg. vol. i (1882) p. 15 & pi. i, 



fig. 1. 



- The patch a represented in fig. 208 of Prof. Gosselet would agree some- 

 what in position with that above described, but it difiers in shape and in being 

 garnetiferous, and has probably been quarried a>?ray. 



I found in a talus-heap near here a loose specimen containing garnets, some 

 of which are about 5 mm. in diameter. 



