Dr. Du Riche Preller—Permian in the Alps. 7 
as at Bourg d’Oisans, has been noted by other writers. Here, too, 
the mineral so abundant in the green veins of Penmaenmawr, which 
Schaub has determined as prehnite,' is at times seen to be intimately 
associated with the axinite. It has a lower refractive index and 
higher birefringence than the latter, and where cleavage-traces are 
developed it extinguishes parallel thereto (001). A genetic relation- 
ship between the two minerals appears to be indicated. 
In all the cases which I have seen recorded hitherto the gaseous 
boron-bearing emanations leading to the production of axinite have 
followed the intrusion of a granite magma. At Penmaenmawr the 
magma was of intermediate calc-alkalic character. It is assumed 
that here, too, the hot gases charged with boron-compounds reacted 
on the original lime-bearing minerals of the veins, releasing the silica 
and forming new combinations with the lime and other constituents, 
and that thus the secondary mineralization of the axinite veins was 
essentially effected. In the Cornish greenstones the production of 
axinite is usually accompanied by ‘‘one or more of the following 
minerals, pyroxene, epidote, hornblende, garnet, quartz, and felspar, 
while zoisite, zincblende, sphene, and fluor-spar are sometimes 
present’. With the exception of quartz, a soda-lime felspar, and 
a little epidote, none of these minerals has been observed in the 
axinite veins of Penmaenmawr. 
The green and other veins, which are so abundant at Penmaenmawr 
and have been previously described, as mentioned above, consist 
predominantly of micropegmatite and orthoclase, with subordinate 
plagioclase, augite, ilmenite, biotite, and apatite. It may perhaps be 
assumed that the axinite veins, which appear to be of very limited 
distribution, were originally filled with predominantly basic material, 
rich in lime; and that this took place at some other period, probably 
earlier in the course of the intrusive episode, than that which saw 
the production of the more acid veins. Somewhat confirmatory of 
this suggestion is the fact that. in the same neighbourhood, viz. the 
most easterly Graig Lwyd Quarry, an interesting vein or patch was 
recently exposed, consisting essentially of calcite and tale, largely 
intergrown with each other. 
1V.—Tue Permian Formation in THE Ars oF Primont, Davpgine, 
AND Savoy. 
By C. S. Du RICHE PRELLER, M.A., Ph.D., M.I.H.E., F.G.S., F.R.S.E. 
. I. Inrropuctory. 
N a recent paper on the Marble District of the Apuan Alps or 
Carrara Mountains*® I showed that the gneissose schists which 
form the nucleus of that range, and upon which rests the Triassic 
marmiferous formation, are, not of Archean, but, upon irrefutable 
paleontological evidence, of Paleozoic age, and that, upon equally 
1 Neues Jahrbuch fiir Mineralogie, Abh., p. 110. 
2 The Geology of the Country around Bodmin and St. Austell (Mem. Geol. 
Surv.), 1909, p. 53. 
3 GEOL. MaG., December, 1915, pp. 554-65. 
