42 General Notes. [ Jan. 
s. Penfield and Harper’ have carefully sgh pure 
aleio eon Greenland, and have eee > to contai 
Mg a H,O total 
4.46 4.27 0.12 0.63 ~ 24: ve eee 18. 73 91.70 
Upon calculation it was found that the amount of fluorine ob- 
tained in the analysis was not sufficient to unite with all the 
metals; hence these authors assume that the metals which are 
in excess of the fluorine combine with hydroxyl. If this be 
true, the ahve n of ralstonite as calculated from the analysis 
is as Seg 
K OH 2 
e aay 0.12 O07 24.25 39:91 -16.27 10.12 = 99.36, 
and the mineral may be regarded as an isomorphous mixture 
of (MgNa,)AI,F,,.2H,O and (MgNa,)Al, (OH). The min- 
eral which best illustrates the power of fluorine to replace 
hydroxyl in a chemical compound is /erderite, which has re- 
cently been shown? by these same investigators to consist of 
an isomorphous mixture of CaBeFPo, and. CaBe(OH)Po,. 
Lucasite, a new variety of vermiculite; from Corundum Hill, 
Macon County, N. C., is described by Mr. T. F. Chatard3 as a 
foliated mineral of a yellow-brown color, with eminent basal 
cleavage and a submetallic, greasy lustre. It dissolves in hydro- 
chloric acid and exfoliates when heated, swelling at the same 
time to twice its original volume. It is biaxial and negative, with 
a small apn angle. he well-known garnet pseudomorphs - 
fromt e Superior region have been examined by Messrs. 
Penfield and Sperry.* According to these gentlemen the altera- 
tion of the garnet consists in a slight oxidation of its iron, a de- 
crease of its silica,an almost total disappearance of its manganese 
and calcium, and an increase in its magnesium, alkalies, and water. 
The resulting mineral is a ferrous chlorite5 with a composition 
approaching that of prochlorite. An examination of a decom- 
posed garnet from Salida, Colorado, yielded the same result. 
Some very fine pseudomorphs of limonite after pyrite are figured 
by T. G. Meem® in the October number of the American Fournal 
of Science, in which the striations due to the oscillation of the 
octahedron and icositetrahedron are well preserved. 
rites.—During the past summer quite a number of short 
articles descriptive of meteorites have appeared in the American 
Fournal of Science. In the June number Mr, W. E. Hidden? de- 
two masses, neither of which was seen to fall. One is a 
meteoric iron, found in Independence County, Ark. It weighs 
ninety-four pounds. A curious feature in connection with it 
* Amer. Jour. Sci., Nov. 1886, p. 380 
Emory and Harper, Amer. Jour, ” Sci., xxxii., Aug. 1886, p. 107. 
"3 Amer. Jour. Sci., xxxii., Nov. 1886, p. 375- Oct. 1886, p. 307. 
a a Ancaster Naturalist, Feb. 1886, p. 161. 
- © Amer, Jour. Sci, xxzii., p: 274... o + Ib., xxxi., N No. 186, p. 460. 
.4 
