+ Eliot ol Mariette. if Nowa Aicciia. = 
given by Heddle* as that of ‘ mesolite,” and also by Berzeliust 
as representing the constitution of “lime-and-soda scolecite.” _ 
It is interesting to observe on comparing this formula, which 
includes those of two of scolecite and one of natrolite, with the 
shen aa eee. that they differ in containing respectively 
three of a monosilicate, and one atom of a sesquibasic 
silicate rs peautinc combined with the same groups of ee 
mae Si0s+Al120:Si0:+3HO scolecite) 
Si0s+ AlzO3:Si03+2HO natrolite) 
_weosio:, 2CaO Si03+38(Al20sSi03s)+8HO ae 
NaOSiOs, 2CaOSiOs +8Al203, 2Si03+8HO faréelite, 
and I am inclined to think that, in the case of minerals occtr- 
ring in such intimate association as these, when there is a choice 
of formula equally according with the results of analysis, that ; 
one is preferable which shows some such simple relation, and 
therefore that Heddle’s formula is more probably the correct ex- : 
pression for fardelite than that of a hydrous nepheline before == 
mentioned. ame 
Epistilbite—I found this species very generally accom any- : 
ing a very fine variety of stilbite on ledges of trap at N arga- 
retville, a village about seven miles east 
eral detached from stilbite gave these results on analysis :— 
NaQ KO CaO AlOs FesOs Si0s HO 
099 099 700 1534 158 5857 1542-99-89 
_ I met with the same substance on a specimen of cae yellow 
stilbite in the eabinet of King’s College, Windsor, » among 
some minerals labelled “ Nova Scotian,” but the precise locality es 
of this one was not marked: in this case it was so inti 
mixed with eale-spar as to render mechanical separation impos- 
oe its analysis which follows shows on this account some car- 
ate 
ela KO AhOw Si0s CaO CO ~—-HO 
trace —-——-:16-10-- ere é as 154  1436=99-68 
after deduction of this accidental adobe the essentials be- — 
come, 
* Edinb. New Phil. Journ, iii, p. 351. 
oh + Fourth Supp. to Dana’s s Min., loc. cit., p. 127. 
SECOND SERIES, Vou. XXVI, No, 76.—JULY, 1958. 
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