﻿Vol. 6 1.] 



DOLOMITES OF SOUTHEEN TYEOL. 



105 



Profs. Doelter & Hoernes 1 recorded two analyses of rocks from 

 the Marmolata, near the Fedaja See, in which the insoluble residues 

 amounted to "06 and *03 per cent, respectively. The analyses 

 indicate that the massif, as a whole, is very free from insoluble 

 residue, and is for the most part not dolomitized. 



The Sella. 



The specimens were collected in sequence from the northern 

 slopes of the Sella Mountain, on descending from the Groden Pass 

 towards Colfusco. No. 101 was taken from a block fallen from the 

 upper part of the mountain ; No. 99 from near the junction with 

 the subjacent St. Cassian Limestone ; while No. 98 represents a 

 specimen of the St. Cassian Limestone, analysed for comparison 

 with the dolomitized rock above it. 





CaC0 3 . 



Mg0O 3 . 



No. 



Per cent. 



Per cent. 



*101 



557 



44-3 



102 



79-3 



20-2 



100 



80-5 



18-2 



99 



81-7 



174 



98 



88-2 



8-2 



Insoluble residue. 

 Per cent. 



V 46 

 1-26 

 093 

 353 



Not in place. 



Taking the results in ascending order, we find that the amount 

 of insoluble residue, which is high in the St. Cassian Limestone, falls 

 on ascending the Dolomite Series, the uppermost specimen being 

 devoid of residue. 



On the other hand, the percentage of magnesium-carbonate 

 rises from 8 in the St. Cassian Limestone to 44 in the dolomite of 

 No. 101, the intermediate specimens being dolomitic limestones. 

 Profs. Doelter & Hcernes 2 recorded an analysis of a dolomite from 

 Schloss "Wolkenstein, west of the Groden Pass, which contained 

 •11 per cent, of insoluble residue. 



The St. Cassian District. 





Lavare 



11a. 







CaC0 3 . 



MgC0 3 . 



Insol. res. 



No. 



Per cent. 



Per cent. 



Per cent. 



82... 



54-7 



45-3 



■033 



81 ... 



54-7 



45-3 



•013 



83... 



55-5 



44-5 



•013 



The three specimens were col- 

 lected, in descending order, from 

 the dolomite-mass of Lavarella, 

 east of St. Cassian. It will be 

 seen that insoluble residue is 

 practically absent, and that the specimens are dolomites of theoretical 



composition. An analysis of a 

 76 ...| 84-1 I 10-2 | 5-73 | St. Cassian Limestone (No. 76), 



from the slopes below Lavarella, 

 shows considerable residue and over 10 per cent, of magnesium- 

 carbonate. 



Jahrb. d. k.-k. geol. Keichsanst. vol. xxv (1875) p. 319. 



Ibid. p. 320. 



