68 JOURNAL OF THE 
phillipsite group of the zeolites, was expected from the 
first on account of its crystalline form, and this relation 
is very satisfactorily brought out by a comparison of the 
crystallographic properties and chemical composition. 
They all have very nearly the same axial ratios: 
0 OG as 
Wellsite....°768 T 23485) p55" ae 
Philhipsite :*70949: > BET" 2563 °: P= 535aF 
Harmotome.*70315 °: : 7°2310 =p=55 10 
Stiblite .... °76227 :1:1°19401 B=50 493 
In their habit and method of twinning, they are also 
very similar, all the crystals being uniformly penetration 
twins. This is especially noticeable between the new 
mineral and phillipsite and harmotome which are common 
as dowble twins with c, 001 and e, O11 as twinning planes. 
The place of the mineral in the phillipsite group is 
clearly shown by a comparison of their chemical compo- 
sitions. Arranged in order of their proportions of silica 
and water to the bases, we have the following interest- 
ing series, in which R represents the bivalent elements: 
Wellsite........RAIS1,0,,.3H,O 
Phillipsite......RAI,Si,O0,,.43H,O 
Harmotonmre..... RAT S07 55.0 
Stilbite ......... RA1Si,0,,.6H,O 
The ratioof RO:AI,O, is constant, 1:1, in the series, while 
the proportions of silica and water have a constant ratio, 
1:1, between themselves, except in the case of phillipsite. 
As there is, however, considerable variation in the analy- 
ses of phillipsite, it is not improbable that the ratio of 
S10,:H.O, given as 4:45, should be in some cases at least, 
4:4, The minerals then form a gradual series, increas- 
ing in the proportions of SiO, and H,O from wellsite to 
stilbite. 
Fresenius® has shown that this group of minerals may 
be regarded as a series in which the ratio of RO:A1,O, is 
#75, Kr., III, 42, 1878, 
