34^2 M. Beudant on the Opals qf Hungary, 
porphyry, on the sides of the Gran, at Bzenicza, at the extremi- 
ty of the valley of Eisenbach. It exists also in kidneys, in the 
pumice conglomerate, at Sajha, near Neusohl ; at Borjh^ on the 
southern declivity of the mountains of Schemnitz ; at the foot of 
the mountain of Sator, and at Szanto, near Taliya, in the group 
of Tokaj ; at Erdo-Benye, he. But the opals of these different 
places are, in general, less perfect^ characterized than those 
which we have j list mentioned ; their fractiu'e is intermediate 
between that of opal, properly so called, and that of flint ; they 
have sometimes a fuliginous tint of colour, and approach to the 
whitish or brownish menilite of the neighbourhood . of Paris ; 
they also pass into opal-jasper, of which we shall speak in the 
following article. 
Opal occurs also in the perlite itself, where it appears in the 
cellules or fissures of the rock. It is thus that it occurs in nests, 
and in small veins in the perlite, at the extremity of the Val- 
ley of Glasshutte, and at Telkebanya, in the trachytic group 
of Tokaj. In the first of these localities, the opals are of 
the whitish opaque, and milky transparent varieties. In the 
second, they are wax-opals, fire-opals, like those which M. de 
Humboldt has brought from Zimapan, at Mexico, whei\e they 
occur in the same matrix. I have never seen this substance in 
other rocks of the trachytic formation : the siliceous matters con- 
tained in the millstone-porphyry {porphyre molaire)^ are always 
in the state of calcedony, of jasper, or flint. 
Opal- Jasper , — Werner has designated by the name of Opal- 
Jasper a particular species of jasper, the basis of which is of the 
nature of opal, and which occurs more or less mixed with 
foreign matters, among which the oxide of iron appears to hold 
the most important rank. Hungary is still one of the countries 
where this substance presents itself in the greatest abundance, 
and that which has furnished the greater number of specimens 
which, we possess in collections. These siliceous matters often 
fill the fissures of different varieties of trachyte in other cases, 
they are found in the form of kidneys, in the midst of altered 
conglomerates ; or, lastly, they ha^■e penetrated into wood depo- 
sited in the heart of these deposits. They present, in these va- 
rious circumstances, different degrees of purity, as well as many 
varieties of colour and general appearance, and pass into each 
