SCIENTIFIC SUMMARY. 
279 
MINERALOGY. 
Plumosite in the Isle of Man. — In the Transactions of the Royal Geological 
Society of Cornwall, Mr. Warington W. Smyth notices the occurrence of 
plumosite in the Foxdale Mine, Isle of Man. The mineral is a double 
sulphide of lead and antimony, and its occurrence here is especially 
interesting as no antimonial minerals had previously been known from these 
mines, which furnish a richly argentiferous lead ore. Plumosite occurs in 
the Hartz, where it is known by the cognate name of Federerz ; in Britain 
it is exceedingly rare. The specimens described by Mr. Warington Smyth 
consist, as usual, of very delicate fibres, which appear to be matted together 
like a tuft of dark cotton-wool. The microscope shows it to form prismatic 
crystals of brilliant metallic lustre. 
Jadeite . — M. Damour has communicated to the Academy of Sciences 
( Comptes Rendus, 6th June, 1881) the results of some new investigations 
made by him upon jadeites and other sodiferous rocks. Jadeite is employed 
in India and China in the manufacture of vases and ornaments, and is also 
met with in the worked state in Europe, in prehistoric burial-mounds and 
caves.* The fact that no stone of the kind has ever been found in the rough 
state in Europe, has led to the assumption that the objects found here were 
imported by immigrants from the East, and M. Damour has investigated its 
geographical distribution with the view of clearing up the question of the 
real origin of the European jadeite axes and ornanents. M. Damour gives 
analyses of undoubted jadeites from Asia, and of portions of worked stone 
possessing the same characters obtained in Mexico, and in comparison with 
these some analyses of minerals obtained in Europe, especially in the region 
of the Alps, which he thinks make out a strong case in favour of the 
occurrence of jadeite in Europe. The following are the analyses of the 
European specimens : 
I. 
II. 
III. 
IV. 
Y. 
YI. 
Silica 
58-51 
56-45 
57-99 
55-82 
56-74 
54-53 
Alumina . 
21-98 
17-02 
20-61 
10-95 
10-02 
14-25 
Ferric oxide 
1-10 
7-62 
2-84 
5-68 
4-69 
3-29 
Chromic oxide . 
— 
— 
— 
— 
0-03 
— 
Lime 
5-05 
4-76 
4-89 
13-42 
14-00 
12-40 
Magnesia . 
1-70 
2-32 
3-33 
9-05 
910 
7*50 
Soda 
11-84 
11-46 
9-42 
6-74 
5-40 
6-21 
Potash 
traces 
traces 
1-50 
traces 
traces 
traces 
100-18 
99-63 
100-58 
101-66 
99-98 
98-18 
Spec. Grav. 
3-35 
3-17 
3-16 
3-22 
3-32 
3-31 
No. I. is a specimen from Monte Yiso, in Piedmont ; LI. from Ouchy, near 
Lausanne ; III. is part of a stone axe ; IY. is a rock from near St. Marcel, in 
Piedmont, where it was obtained from a small vein ; Y. from a pebble from 
* See an article by F. W. Rudler in Popular Science Review for October 
1879. 
