14 RECOHDS OK THF AUSTRALIAN MOSETM. 



readied after traversing a number of galleries and coi-iidors to a depth of 

 appioximately tln-ee hundred feet for a distance of about eighteen chains. 

 Across one corner of this chamber is an overhanging ledge draped with a 

 curtain of stalactite growth and forming a sort of shelf about ten feet 

 above the floor of the cavern ; it was in this ledge that the crystals were 

 discovered by Mr. W. F. Hosie, of Carlton, a station property in the 

 vicinity. When the ledge was broken into from above a lense shaped 

 opening, measuring approximately eight feet long, four feel wide, and 

 eighteen inches high was revealed, the bottom, roof, and sides of which 

 were studded with beautiful groups and single crystals of tiansparent or 

 translucent calcite; the largest crystals, some of them eight inches in 

 length, are clustered round the edges where the roof and floor of the 

 cavity meet. The cavity has bden broken into at both ends, and when it 

 is illumined from one end and viewed through the other opening it 

 presents an aspect of rare beantj'. 



Probably the solution from which the crystals were deposited formed 

 at one time a quiet pool in what was then the floor of the cavern. 

 Usiiall}' the water in limestone caves is in constant circulation, a stream 

 flowing along the floor, and the roof and walls continually dripping with 

 the lime-beaiing solution from which the stalactites and stalagmites 

 are formed, bat these crystals could not have been deposited under such 

 conditions. Probabl}' the pool in which they developed was a kind of 

 backwater, perhaps formed by the accumulation of the clayey residue of 

 the dissolved limestone which seems to have been highly argillaceous. 

 This pool became crusted over with a crystalline deposit which now 

 foi'ms the roof of the vugh and is about five inches thick. The carbonic 

 anhydride would then escape very slowly from the saturated solution 

 which would remain more or less constant in temperature, and the 

 conditions generally would be favourable for the growth of well formed 

 crystals. That the conditions were uniform throughout the period of 

 formation of the crystals is indicated by their striking uniformity of 

 habit. 



The ci'vstals are relatively simple, the forms repi'esented being 

 a (1120), )// (1010), r (1011), M (404.1), and/ (0221) ; of these M and/ 

 predominate and give the crystals their characteristic pointed shape 

 (PI. iii., tigs. 1, 2; PI. iv., fig. 5). The prism m and the rhombohedron /• 

 appear as narrow planes and are absent on niany of the crystals. The 

 second order prism a is usually present as a rounded face, convex or 

 concave, giving on the goniometer a train of signals 13'ing in the zone 

 [a ?•], the face being striated pai-allel to this zone axis (PI. iii., fig. 2; 

 PI. iv., fig. 5). In the beautiful gioiips shown in PI. iv., figs. 2, 4, some 

 of the crystals look like simple rhombohedra through the piedominance 

 of /*, although M is also present as small triangular planes. The faces of 

 3/ are smooth and brilliant but/ is frequently rounded and imperfect, 

 with triangular etch pits, the edges of which are parallel to the 

 intersections of/ with iii,f' and/'' (PI. iii., tig. 1) or irregular nuirkings 

 (PI. iii., tig. 2). The crystals have usually one good termination, the 

 other, which was the point of attachment, being broken and irregular. 



