164 F, L. Stillwell: 



be precipitated before some of the gold, and some of the gold 

 before some of the pyrite. The mutual relationships of the 

 solubilities and concentrations of the different vein minerals, 

 which might have been expected to produce a more or less 

 characteristic order of deposition have been disturbed by the 

 presence of foreign precipitating matter. 



A specimen of a different and rare type at Bendigo is illus- 

 trated in Fig. 3. It consists of a thin plate of gold, with a small 

 fragment of attached quartz, terminating in a crystal of gold. 

 The specimen is 3 cm. long, weighs 2 dwts. 14 grs., and is shown 

 in the photograph with a magnification of 2. It was found in a 

 ■quartz spur in sandstone about two feet wide in the stopes on 

 the Victory spurs, 580 feet south, 1235 feet level, in the CarHsle 

 mine. The gold crystal occurred in a vug, terminating the plate 

 of gold in the same way as the associated quartz crystals in the 

 same vug grew out from the mass of quartz. The dominating 

 faces of the crystal are those of the octahedron. The solid 

 angles of the octahedron are replaced by small faces of the 

 cube, and the edges of the octahedron are replaced by faces of 

 the rhombicdodecahedron. For nearly 1cm. behind the ter- 

 minating crystal, crystalline faces of gold can be seen on the 

 plate of gold. It is quite clear that this small nugget of gold 

 is as essential and primary a part of the vein as the quartz 

 crystals that form the bulk of the vein. Had the gold not 

 assumed the platy and crystalline form, the occurrence might 

 have been similar to the gold wire whose occurrence in a quartz 

 vug has previously been recorded. ^ 



Another rare specimen obtained from the same stopes, at the 

 1235 feet level, in the Carlisle mine, is illustrated in Fig. 4. This 

 is a fragment of a very small, but very rich, spur, which traversed 

 a thick bed of slates on the eastern side of the stopes. The 

 thickest part of the vein in the specimen is 5 mm., in which are 

 ■embedded two isolated crystals of sphalerite, with a little ad- 

 mixed pyrite. A few small specks of gold are embedded in 

 the quartz, but the main mass of gold in the specimen occurs 

 as a thin film, bounding the quartz and the slate. The gold film 

 •shows irregularities, but is fairly continuous, and, when the 

 slate is broken away, has the appearance of gold paint on the 

 wall of the vein. Towards one end of the specimen the thick- 



2. The Factors Influencing the Deposition of Gold in the Bendigo Gold- 

 ■fleld. F. L. Stillwell, Bull. No. 8, Adv. Council of Scl. and Industry, Plat6 

 ^., fig. 2. 



