The quantity of iron which the mine of Dannemora yields in a
year amounts to above 4000 tons. There are other Swedish mines
that yield much more iron, though not of so good a quality.
The soil round Osterby is uncommonly sandy. During the last night
that I was there, it rained furiously for many hours ; yet next day the
road was quite dry, and no traces of the rain could be observed.
About seven miles south-west from Dannemora, at a place called
Gokum, there is a lime quarry which deserves to be mentioned. The
limestone is primitive,-and yields, according to Rinman, 16 per cent,
o f iron. This limestone contains tremolite; it contains likewise another
mineral, which has attracted some attention in Sweden- It was
first described and analysed by C. A. Murray. Afterwards another
description by Lobo, the Portuguese Ambassador at that time in S weden,
and analysis by Berzelius, were published. Lobo gave it the name
o f Gahnite, in honour o f assessor J. G. Gahn, at Fahlun. This mineral
1 had an opportunity o f seeing by the politeness o f Mr. Tamm, who
presented me with a specimen o f it. I shall here give a description of
its characters and constituents.
Its colour is dark olive green. Its specific gravity 3*543.
It scratches glass; but is itself scratched by quartz— brittle and
easily frangible.
Gross fracture uneven and fine granular, splintery, here and there
passing into small conchoidal. Longitudinal fracture foliated.
External lustre strongly shining; internal, feebly shining; lustre between
resinous and vitreous.
Fragments indeterminate angular; angles not particularly sharp.
In thin splinters it is translucent.
Before the blowpipe, upon the point o f a platinum wire, it melts
pretty easily into a yellow brown porous glass, frothing a little at the
commencement. With borax upon charcoal, it melts into a sea green
glass bead.
It shows no signs of electricity, either by rubbing or heat.*
* The above description is translated from Lobo. Not having my own specimen, I
durst not venture to make any alterations in it from memory.
The constituents of this mineral, according to the analyses o f Murray
and Berzelius, are as follow;
Murray.* Berzelius.t
Silica....................
Lime.................. . . . 37*65
Alumina............. . . . 17*87 . . . . 1 . 17*50
Magnesia........... j . . . 2*78 . . . . . . 2*52
Oxide of iron. . . . . . 6*75 . . .
Oxide of manganese 0 *3 1 0*00
Volatile matter. . . . 0*25
98*17 9 9 *2.8
Loss................... 1*83 0*72
100*000 100*000
The term Gahnite had been previously given to other minerals.
The substance called Fahlunite, to be noticed hereafter, is sometimes
distinguished by that name. This circumstance, though intended to
do honour to a man highly deserving o f such a distinction, is unfortunate
; because it has a tendency to throw confusion into a branch o f
knowledge already unhappily remarkable for a prodigious multiplicity
of redundant names. Many people seem to aim at the distinction of
conferring new names, as i f it were the only means of acquiring eminence
in mineralogy, a branch o f science which requires, above- all
others, accurate powers of discriminating.
It would be improper, while giving an account o f the minerals o f
Upland, to pass by the quarry of Ytterby, become famous from the
curious substances that have been found in it. It lies rather less than
two English miles north from the fortress of Yaxholm, and consists of
a rock obviously connected with gneiss, that constitutes the basis o f the
country; though it consists chiefly o f beautiful white felspar, and fel-
* Afhandlingar i Fysik, Kemi och Mineralogi Utgifiie af W. Hisinger och J. Berzelius,
Vol. II. p. 179.
t Ibid. Vol. III. p. 276.
2 C