SILICA. 



:}09 



ARFWEDSONITE. 



[In honor of Professor Arfwedson.] 



Arfwedsonite. Phillips. — ArfveJsonite. Tliomson. — Peritomcr Augit-Sfatli. Mohi. - 

 name as one of tlic synonyms under his Petalile.) 



■ (Bcudant refers lo this 



Description*. Colour pure black, without a shade of green. Streak 

 greyish green. It has only been observed in cleavable masses. Primary 

 form an oblique rhombic prism.* Fig. 2.51. M on M' 123° 55' (horn- 

 blende being 124° 300- Cleavage parallel with the sides of the prism, 

 producing more brilliant faces than those of hornblende. Lustre resinous. 

 Opa((ue. Hardness 4.5 (Thomson), 6.0 {Phillips). Specific gravity 

 from 3.40 to 3.50. Before the blowpipe, it melts easily, with intume- 

 scence, into a black globule; with borax, it yields a glass coloured by iron. 



Composition. Sihca 50.51, peroxide of iron 35.14, sesquioxide of manganese 8.92, 

 alumina 2.49, lime 1.56, moisture 0.96 {Thomson.) 



LOCALITIES. 



Found at Kargardiuarduk in Greenland, associated with sodalite and eudialite. It was 

 known by the name oi ferruginous Iwrnhlendc, until it was shown by Mr. Brooke that the 

 measurements of its crystals did not agree with those of hornblende. 



A mineral closely agreeing with the description of arfwedsonite, is found associated with 

 epidote, garnet and magnetic iron ore, in Putnam county, two miles south of the village of 

 Carmcl. It has a jet black colour, and is made up of coarse fibres having a high lustre. It 

 is less hard than hornblende. Before the blowpipe, it fuses, with some bubbling, into a black 

 glass, which is powerfully attracted by the magnet. 



HYPERSTHENE. 



[From the Greek u*jp, above, and (ffcvojr, strength; because it is harder than hornblende, for which it 



was mistaken,] 



H3rpersthene. Haliy, CUavdand, Phillips, Tliomscm and Bcudant. — Paulite. Wcriicr. — Labrador Horn- 

 blende. Kinran. — Prismatoidal Scliillcr Spar. Jameson. — Prismatoidischcr SchUler-Spath. Mohs. 



Description. Colour greenish and greyish black ; also copper-red and brown. Streak 

 greenish grey. It occurs in lamellar concretions, which have a cleavage parallel with the 

 diagonals and sides of a rhombic prism of about 93° and 87°, (98° 12' and 81° 48' according 



" Dr. Tliomson remarks, lliat as no cleavages can be observed parallel lo llie base, \vc are ignorant whether the prism be rislit 

 or oblique. Outlines of Mineralogy, Geology, ^c. 



