210 _ SJ. D. Dana’s Mineralogical Contributions. 
These results give on calculation : 
Ca? oe si Ca Fl 
I. 93-77 3-04 
Il. 93°54 15 8 02 
The analyses agree well together, fii give too small a quan- 
tity of chlorid and fluorid of calcium. 
at 
Arr. XXI. ra wpiasions to Chemical Mineralogy ; by 
James D. Dana.—Part IL. 
1. Relations of Anhydrous Carbonates and Sulphaies. 
Te Carbonates that come under the general formula 8 6, and 
the Salphades RS, present each a case of trimorphism : and a 
third example of similar character is ort in the coma 
of Sulphates and Carbonates (RS4nRC). These cases are as 
follows; the angles given are R: R in the rhombodedral forms, 
and I: I (oo P) in the Amory — 
Rhombohedral. Monoclinic (basal cleavage). 
Calcite, GaG; 105° 05’ Pras res 116° 10’ nee ferent (Ca, Ba) 6; 
{ Anglesite, PbS; 108° 88”) 
Dreelite,(Ca,Ba)S; 93-94° { Anhydrite, Pe srs - ’ Glauberite, (Ca, Na)5; 83° 
Barytes, Ba 8; 
soe PbS+3hv6; — a Pb S4aPb0, ae Lanett: PoS+Pbd © 
nd 
nd 
There is a sihuokcabe cuales between ss sulphates @ 
carbonates. ‘The difference between the angle of Atragenias® ” 
Calcite is about Ll degrees; between Calcite and Barytoca 
10 degrees. Nearly parallel with this, the angle in Anglesite 
Avhydrite is about 10 degrees larger than that in Dreelite, and 
that of Dreelite is 10 degrees larger than that of Glauberite. 
The sul phatocarbonates correspond with the sulphates ieee in 
angle, and confirm this parallelism. Susannite and Dreelite 4 
nearly the same in angle; so also Leadhillite and 1 
and Lanarkite and Glauberite.* 
It hence follows that the homologous prisms in er 
and Anglesite are the prisms, above mentioned, of 116° W 
angle of Susannite mentioned iy Haidingtr is that of oR, Brooke - 
Miller give Leadhilit another position which makes the angle I: 1 
‘It is pret rg oe his is not the posi position, from the fact that the 4 with 
he carbonate and sulphate of lead, or ident ition, 
one posts ot! uch larger than that of th nate ther pos 
g 1% as I, we have I © 16’, or An This view pest) 1 
taking 17 as ; or near Anglesite. 
by — of Susannite (which is identical with Leadhillite in compos" 
Lanarkite, according to measuremen R. P. Greg, Esq., recently Cag i 
cated to the writer, the oceurring vertical ee Bagh! has the front angle 49° 50’; a” 
this being taken as the prism i2 (x P’2), makes I: 1= 85° 48’, as above state 
