68 
PROCEEDINGS OF SOCIETIES. 
Professor Jukes instanced cases in England in which large blocks of 
rock had been carried from south to north, probably by secondary cur¬ 
rents to the north. 
Mr. J. Beete Junes read a paper by M. Alphonse Gages, Curator of 
the Museum of Irish Industry— 
ON PSEUDOMORPHIC TREMOLITE INCRUSTED WITH CARBONATE OF LIME AND 
MAGNESIA, BEING APPARENTLY THE MINERAL DESCRIBED BY DUFRENOY, 
UNDER THE NAME OF MIASCITE. 
In the supplementary part of his “ Traite de Mineralogie,” yoI. iii., 
p. 770, Ed. 1845, M. Dufrenoy has described, under the name ofMiascite 
(Miaskite), two very distinct substances. 
The first is a grayish felspathic rock, composed chiefly of felspar 
uniaxal mica and eheolite. It was first described by G. Bose in the 
account of the journey of Humboldt, Ehrenherg, and G. Bose, to the 
Ural Mountains. 
The name of Miaskite was given to this rock from its occurrence in 
the hills in the neighbourhood of Miask, in Siberia. 
The second substance described under the name of Miaskite was 
also derived from the same locality just named, whence it was sent to 
M. Adam. M. Dufrenoy examined it, and considered it to be dolomite. 
In examining the collection of minerals in the Museum of Irish 
Industry, I found a specimen labelled “Miaskite,” and answering per-’ 
fectly to the description given by Dufrenoy of the substance examined 
by him. 
The remarkable structure of this mineral, formed as it were, of a series 
of crystalline fibres arranged parallel to one another, may be . compared 
to a bundle of flax or of thread, completely incrusted with saline matter, 
the crystals of which have disposed themselves in the direction of the 
fibres. This peculiar structure gives it the aspect, at first sight, of 
fossil-wood, but a close examination led me to suspect that it was the 
result of pseudomorphic action. Having removed a fragment of the ex¬ 
ternal part of the specimen by splitting it in the direction of the fibres, 
I introduced it into very weak hydrochloric acid; the result obtained 
after some days of contact with the acid confirmed my supposition: 
the acid dissolved a quantity of lime and magnesia, and left an asbestos¬ 
like skeleton. 
Having submitted another portion to analysis, the following num¬ 
bers were obtained as the result:— 
Carbonate of lime,. 57-483 
Do. magnesia,.40-510 
Sesquioxide of iron and alumina, . . 0*375 
Asbestiform skeleton,.1-595 
Water and organic matter, . . . . 0-239 
100-202 
