733 
passing notice. Had circumstances been more kindly, the yellow glass would have 
teemed with crystals and crystallites. After reading Professor Judd’s last Paper on 
“ The Rejuvenescence of Crystals,” one cannot help musing on the barrenness of a 
soil so capable of sustaining crystal life. 
BASALTS. 
But little description is necessary of this group of rocks, for the name is old and 
the rocks are familiar under that name to most. There are three varieties of basalts : 
basalts proper, anamesites, and dolerites ; names denoting difference of structure or 
texture rather than mineralogical variation. 
I. Basalt proper is compact, amorphous, often semi-vitrcous, breaking with a 
perfectly conchoidal fracture. 
II. Anamesite (from ava-peo-os, intermediate) is uniformly crystalline, but close- 
grained, the crystals being very small. 
III. Dolerite is coarsely crystalline, the word signifying deceitful, a name 
suggested by the difficulty of distinguishing it from certain Plutonic rocks. 
Zirkel classifies the basalts mineralogically into — ■ 
1. Pelspar-basalts. 
2. Nepheline-basalts. 
3. Leucite-basalts. 
Mohl divides the members of the basalt group into — 
1. Magma-basalts, with a colourless or brown-glass matrix. 
2. Plagioclase-basalts, containing notably plagioclase and occasionally nephelene 
in addition to the essential augite, magnetite, &c. Leueite seldom. 
3. Nepheline-basalts, containing notably nepheline, and sometimes leueite, in 
addition to augite, magnetite, &c, Plagioclase rare or absent. 
4. Leucite-basalts. 
5. Hauyne and nosean-basalts. 
6. Mica-basalts. 
Eutley says : — 
“ In microscopic sections of basalts which have undergone partial decomposition, 
the olivine and augite crystals are often merely represented by pseudomorphs of green 
matter, which is serpentine or some other hydrous silicate. The augite in basalts is 
generally rich in glass enclosures. Steam pores and fluid lacunse are also of common 
occurrence in them. The olivine sometimes appears in tolerably well-defined crystals ; 
but it is more usually in roundish grains, or in granular aggregates. The latter are 
sometimes of considerable size, and occasionally show, in external configuration, that 
they are large, rudely-developed crystals. The plagioclase basalts are of more frequent 
occurrence than any of the other rocks belonging to the basalt group.’’* 
The most interesting of the basalts, described in the foregoing pages, is the 
leueite-basalt from the Hormanby Reefs of the Cooktown District. This is the first 
occurrence of leueite noted in Queensland. The Mineral Census of Australasia f 
(including only the Colonies of New South “Wales, South Australia, Queensland, and 
New Zealand) records only three places where it has been recognised. They are— 
1. Leueite-basalt, Castle Point, New Zealand. 
2. Byrock, County Cowper, N.S.W. (T. W. E. David and W. Anderson.) 
3. El Capital!, County Cambelego, N.S.W. , in a basaltic lava sheet. 
* F. Eutley. The Study of Rocks, page 254. . ^ a • tt 
t Report of Committee, No. 7 ; Mineral Census of Australasia. Proc. Austr. Assoc. Adv. bci., ii. 
1890, pp. 213-273. 
