Sir Charles Giesecke m Cryolite. 14S 
crystallised in imperfect octahedrons; the arsenical pyrites iS' 
partly massive, partly crystallised in oblique four-sided prisms ; 
the iron-pyrites occurs only disseminated. 
At a distance of about 120 fathoms from this spot, there is? 
an extensive bed of large quartz crystals, similar to those found 
near Zinnwald in Bohemia ; but they are throughout in a per-^ 
pendicular position, some of them measuring a foot in lengthy 
and from 4 to 5 inches in thickness, containing small imbedded 
crystals of tinstone, of the above mentioned forms.^ This bed is 
/ intersected by a nearly vertical vein of compact fluor, of the 
thickness of from 6* to 7 inches. The whole is equally exposed 
to the** tide. The fluor contains no metallic substance, but it is 
of a singular nature. Its colour is reddish blue, verging to« 
wards lavender-blue ; the substance is dull, soft, and presents ra- 
ther blunt-edged indeterminably angular fragments. Its pow- 
der is reddish-white. It emits a strongly hepatic smell when- 
rubbed. The common kind of compact fluor occurs along with it. 
The cryolite rests upon the gneiss, which contains the sub- 
stances just enumerated, and forms two distinctly different bedsy 
which are nearly of the same dimensions, namely, 10 fathoms^ 
in length, and from 5 to 6^ in breadth. The purest cryolite is 
that of a snow-white colour, without any intermixed foreign 
substance, if I except a few nearly minute spots of galena. 
Its colour passes gradually into greyish-white, when it ap- 
proaches to the other bed. The greyish-white variety on the 
surface very much resembles ice, which has been corroded and 
grooved by the power of the sun’s rays. In these Assures, we 
sometimes observe the threefold cleavage of this substance beau- 
tifully displayed. Fragments of quartz and sparry iron-ore in 
rhombs sometimes occur in the greyish-white variety. 
The other bed is separated from the former by an elevation 
of the underlying gneiss, and has a very diflerent appearance. 
The snow-white and greyish-white colour is changed gradually 
into reddish-white, and passes, in proportion to the quantity of 
the imbedded metallic substances, into orange-yellow and brown- 
ish-red* We find, in the reddish- white variety, quartz crystals 
and particles of flesh-red felspar; in the orange-yellow and 
brownish-red varieties, sparry iron-ore, iron-pyrites, copper-py- 
rites, and galena, occur in great abundance.. Sparry iron-ore oc- 
curs massive, and in rhomboidal crystals, accumulated in groups 
