Chlorastrolite and ZojiocJilorite . — Winchell. 1 1 7 
few scattered spherulites of delessite. Whatever the impurities, 
whether of quartz, delessite, oxide of iron or prehnite, it is ap- 
parent that they have no part in the true nature of the min- 
eral itself. It is quite likely, however, that, in making a chem- 
ical analysis, these would be included, and they probably ex- 
plain the lack of homogeneity which such analyses reveal. 
These impurities do not affect the purity of the surrounding 
fibres. 
The mineral has a strong individuality, as to fibrous, stell- 
ate structure, and constancy of optical orientation, as well as 
to color. It is quite likely therefore that if an analysis be 
made so as to exclude the inclusions which are foreign to the 
mineral proper, its chemical characteristics will be found as 
distinct as its physical. Following is the analysis given by 
Whitney:* 
Si02 36.99 
AI2O3 25.49 
Fe^Os 6.48 
CaO 19.90 
NasO 3.70 
K2O 40 
H2O 7.22 
100.18 
Localities. On Isle Royale this mineral is found at Chip- 
pewa Harbor, Lucky bay, and Rock Harbor, all on the south 
shore and in the same stratigraphic horizon. 
Zonochlorite . Many of the pebbles of chlorastrolite have 
not the characteristic structure and beauty which have made 
them celebrated amongst lake Superior minerals, but present 
in general a dull green color and probably should not be 
allowed the name of chlorastrolite. This general greenness is 
sometimes quite dark, and in other cases it seems to fade into 
a very light green resembling that of lintonite, in the same way 
that mesolite fades in color into lintonite. In a similar man- 
ner it fades out into a white structureless substance whosie 
hardness is less, but also sometimes into a pinkish zeolitic 
♦Geology of the Lake Superior Land District. Part II., p. 97, 
1851; Jour. Bos. Soc. Nat. Hist., V. 488, 1847. 
