136 FIELD COLUMBIAN MusEuM—GEOLOGY, VoL. III. 
Observed Calculated 
mh m os = (110) A (110) = 78° aes vr oot 
DAA ese (2 10 NMA ECA a) 7 44° 2977 44° NST 
a = (010) A (120) = 31 eae ey et ag 
BO aAgey = J (OTO) aati so) = 22° ie 22° 14’ 
oA Oo = (011) A (011) ss 14° 27°" ey aueeas 
Ce Athe en (OOl) a Ayn Gla) — OA EEO. 64° 19’ 
CNG FT = (001) A (113) = 34° 4O" | 34 aa. 
cA q = (oor) A (114) = 27° 34.5 penne 
cA Y = (o01) A (122) = 57 10) 7 ee eee 
ONY =i OTN ure tea) = | 96% Ries 26° ir 
BERTRANDITE 
ALBANY, MAINE 
FIGS. 4-5, PLATE XLVII 
In the summer of 1902, Mr. C. C. Spratt, at that time a resident of 
North Bridgton, Maine, submitted to one of the authors some hand 
specimens showing small, colorless crystals, which proved on examina- 
tion of their blowpipe characters to be bertrandite. Mr. Spratt 
kindly indicated the locality from which the specimens were obtained 
and this was later visited by one ofthe authors. The locality is an 
area of coarse pegmatite in the northern part of the town of Albany, 
Maine. The pegmatite exhibits the usual coarse crystals of quartz, 
feldspar, tourmaline, mica, and beryl and has been worked to some 
extent to obtain the two latter minerals for economic purposes. The 
bertrandite was nowhere found to be abundant, but by close searching 
could occasionally be obtained. It occurs in single or grouped crys- 
tals implanted upon quartz or lining cavities one or two inches in 
diameter. In one of these cavities a considerably corroded piece of 
colorless beryl was found suggesting that the bertrandite may have 
been derived from alteration of the beryl. The crystals of bertrandite 
obtained (Mus. No. M 6969) are for the most part colorless to pale 
white and transparent to translucent. Some are covered with a rusty 
coating which readily dissolves in hydrochloric acid. The crystals all 
show a tabular habit produced by extensive development of the basal 
planes. In habit they thus resemble the crystals of Mt. Pisek and 
Mt. Antero rather than those described by Penfield * from Stoneham, 
although the latter locality is near Albany. The largest crystal of 
* Am, Jour. Sci., 1889, 3, 37, D» 224. 
