386 The American Geologist. Juii(>,i898 
the mica, oligoclase and orthoclase. There has been considerable 
recrystallization in these granites, which has affected the biotite, the 
oligoclase, the microcline and the qnartz as well as 'the secondary 
minerals, and has thereby more or less altered the original structure. 
-Ml the granites show the effect of pressure, but are distinctly sep- 
arated by mineralogical composition from the gneisses. A crushed 
variety of the fine-grained granite is a granulite- associated with the 
Dyneboda gneiss. 
The mica-quartzyte belt is at its base a pure quartzyte. The hem- 
atite ore which this quartzyte contains is concentrated in narrow bands 
which are sometimes folded. The conglomerate, contained in the 
overlying mica-schist, is composed, for the most part (95 per cent), 
of boulders resembling the quartzyte beneath and for the remainder, 
of vein material. The mica-schist, or uppermost member of the 
mica-quartzyte band, is rich in muscovite and alumina minerals such 
as andalusite, cyanite, ottrelite and fibrolite. From this formation 
the author has elsewhere* described a "manganandalusite" which 
lias the physical properties of common andalusite with the exception 
(if a grass-green color and a strong pleochroism. The mica-quartzyte 
belt is connected with the conformable underljnng dense fine-grained 
gneisses through gradations of mica-schist. Dr. Backstrom con- 
siders it possible, therefore, that the granite, being younger than the 
gneiss, is also younger than the mica-quartzyte. But none of the 
rocks of the latter formation now exhibit any distinct proofs of an 
original contact structure, the later tectonic movements having 
obliterated any older structure. 
Amphibolites are associated subordinately with all the formations 
of the region, except the granites. Their principal occurrence is 
as a bed 100 meters thick between the quartzyte and the fine-grained 
gneisses. This bed, it is supposed, has been folded and appears as 
t\yo beds enclosing the quartzyte. This amphibolite is composed of 
hornblende and plagioclase with subordinate biotite, orthoclase, 
quartz and epidote. Structurally three varieties are distinguished by 
the character of the hornblende: the feldspar always occurs in small 
anhedrons; the hornblende and mica may occur in anhedral grains 
or the hornblende occurs as idiomorphic prisms in a feldspathic 
ground-mass, or, finally, it may appear as large irregular grains. 
These amphibolites have the chemical composition of a diabase and 
the mineralogical and structural characters which have been known 
to be produced by the action of contact-metamorphism on a diabase. 
They lie within the contact zone of the granites, already described. 
For these reasons the amphibolite bed is thought to be either a' 
diabase-flow or a layer of diabase tuff, while some of the minor 
occurrences of amphibolite are considered to be altered dyke rocks. 
In the Vestana region there are no unaltered diabases, gabbros or 
diorytes older than the intrusive granites or older than the orographic 
movement. There are, however, numerous .dykes of unaltered 
♦Geologiska Fftreniugens FOrhandlingar, Stockholm', 1896, 18, p. 389. 
