Brush (Hid Dana,— Mineral Locality at Branohville, 218 





[37*69*] 



-f- 142 = -265 = 1-00 = 1 



UnO 



3-42 



IT It) 



T It = :Sin-292- i-io = i 



-T- 1 1 = '245 ^ 



OaO 



30 02 



h- ;»»; = •;, = -2-ivi ss 2 





9 81 



-*- IS = -545 = 2-06 = '2 



Quarts 



1-66 





100.00 



The formula is hence essentially Ca,Mn(P0 4 ) a +2H 2 0, which 

 requires P,0 6 3934, Mn019;67. CaO 31-02, H.O 997= 100. 

 This analysis confirms the earlier one by Penfield and farther 

 makes it probable that there is a definite ratio of 1 : 2 for 

 Mn (with Fe):Ca. 



DlCKINSONITE. 



One of the most remarkable and novel of the species first 

 described from Branchville was the chlorite-like dickinsonite — 

 a mineral of a bright green color, micaceous structure and 

 pst'udo-rhombohedral form. Recent developments have en- 

 abled us to add materially to our knowledge of the species. 

 The number of specimens obtained is relatively large and in 

 some of them it shows itself in tolerably well-defined crystal- 

 lized forms. It will be remembered that for our earlier work we 

 had only one or two minute crystals. The habit of most of 

 the crystals now found differs from that before described, fig. 

 5, the hexagonal form is rather rare and the crystals appear as 

 rectangular tables united in slightly diverging groups, fig. 6. 



5. 6. 



A closer examination shows that they agree w T ith the same 

 fundamental form before accepted. These crystals are elon- 

 gated parallel to the orthodiagonal axis, and the basal surfaces 

 are bent and striated in this direction. In addition they show 

 on the edges, sometimes in traces only, the pyramidal planes, 

 which when developed give the hexagonal habit before noted. 

 In addition to the planes a. 6, c, x (301), /> (111) and 8 (^21), we 

 have identified also a steep clinodome, n, which has the symbol 

 (051) and a hemi-orthodome, y (103). We retain our former 

 axial ratio 



# a: b:c= 173205: 1 : 119806; ,3=61° 30\ 

 * By difference. 



