Prof. How on the Mineralogy of Nova Scotia. 129 



tical observation with reference to cyanolite is, " probably the 

 same mineral with centrallassite, impure with much more silica ; 

 or it is chalcedony, impure with centrallasite " (Mineralogy, 

 Supplement to fifth edition, p. 797). This, of course, may be 

 the case ; but if so, it is curious that the whole of it should 

 have the same composition, as my two analyses would seem to 

 show. In any case, I have no doubt Dr. Burghardt is incor- 

 rect when he says " cyanolite is simply okenite " (Chemical 

 News, vol. xxx. p. 185). 



With regard to centrallassite, it had, in all probability, many 

 years before I came to this country attracted the attention of Dr. 

 Abraham Gesner, who was one of the earliest collectors of mine- 

 rals in this his native province, and was probably more familiar 

 with its choice localities for trap species than any one else has 

 ever been. My reason for saying this is, that after my paper was 

 published I observed in his ' Remarks on the Geology and Mine- 

 ralogy of Nova Scotia,' 1836 (p. 202), the following:—" This 

 mineral, called prehnite, found a few miles east of Black Rock, 

 occurs in small botryoidal masses, of which none were larger than 

 a hen's egg. It consists of very delicate crystals radiating in 

 all directions from the centre. A number of these small cir- 

 cular clusters are collected together, each having its fibres pro- 

 ceeding from an adjusted Centre to the extremity of the group 

 composed by them ; its colour is pale green, supposed to arise 

 from the green carbonate of copper also found near it. Before 

 the blowpipe it intumesces and melts to a spongy black enamel. 

 It does not gelatinize, and is therefore distinguished from zeo- 

 lite. It appeared in amygdaloid near its junction with super- 

 imposed basaltic trap. Locality visited next spring ; no more 

 mineral found." 



Now in this extract I see an accurate description of part of 

 the nodule described in my paper of 1869. Gesner gave no 

 analysis ; but the " intumescence before the blowpipe," while 

 it is a character belonging to prehnite, agrees closely enough 

 also with my statement with regard to centrallassite, • - fuses 

 readily, with continued spirting, to an opaque glassy bead." I 

 find, on repeating the experiment, that the spirting is accom- 

 panied by intumescence. As respects the green colour, that 

 is no doubt accidental ; it is frequently seen in minerals pro- 

 perly colourless, in these districts ; and it is caused, as Gesner 

 supposed, by copper, as I showed in the case of laumonite 

 found in the same range of trap at Margaretville (Edin. New 

 Phil. Journ. 1858). Again, like centrallassite, his mineral 

 did not gelatinize ; and moreover the locality agrees with 

 mine, estimated to be some very few miles east of Black Pock, 

 as it was between this and Hall's Harbour, about eight miles 



