144 P. SGHEI. 



strong weathering has brought about the formation of the 

 cave. Lumps of rock gathered among the caohnite dust at the 

 bottom, show a spongy structure, the original quartz and prob- 

 ably much of the feldspar being carried away and the rest left 

 as a porous mass ; here new formed quartz crystals with calcite 

 and yellow desmine have aggregated. The latter mineral has 

 been identified by an approximate measurement of the prismatic 

 angle, giving 63° 1' (61" T Dana: Syst. Min.). It shows the 

 sheaflike forms in rediating arrangements so very common in 

 that mineral. 



6. Monazîte from Søndeled, Risør. 



Among a number of crystals of monazite kindly shown to 

 me by the owner, Mr. A. Guldberg, M. E., I perceived some 

 few ones, labelled Søndeled, Risør, of a somewhat unusual cha- 

 racter. These specimens were afterwards bought by the Mine- 

 ralogical Institution of the University. 



A little later, Prof. Dr. Brøgger brought to the Institution as 

 a gift from Mr. Jensen, Risør, a pair of crystals, which, upon 

 closer inspection, were found to be of the same type. 



The mineral in question is derived from some pegmatite 

 veins in the neighbourhood of the said township of Risør; 

 it is often quite fresh, brownish in colour with a resinous luster. 



The peculiar thing about it is the crystallographic habit, 

 nowhere observed before among the numerous and greatly var- 

 ying occurrences of this mineral in southern Norway, of which 

 a revision will be given at another opportunity. 



Single individuals occur as well as twins, bounded both of 

 them by the forms jlOOj and jlll| only and prismatic to short 

 prismatic or pseudorhombohedral in appearance (Fig. 6). Fig. 7 

 (side view) illustrates a case of the common type of the single 

 crystals, within which a small lamellar individual is formed 



