352 Dr.Wackenroder's Mineralogical and Chemical 



" Sometimes a combination of several individual crystals is 

 seen. One end of the crystals is always fractured, while the 

 other often shows a tendency to a summit. 



" Besides the marked cleavages of E', those of B' and B are 

 also perceptible. Besides the cleavages, we perceive fissures ; 

 also transverse fissures, which are sometimes irregular and 

 sometimes corresponding to the planes D'." 



The fracture of diopside is imperfectly conchoidal and splin- 

 tery. The angular pieces which are detached from it are fre- 

 quently tabular and prismatic. 



Its colour is a pistachio-green or olive, but sometimes runs 

 in the same prism from greenish white to colourless. 



The crystals are usually translucent only, sometimes trans- 

 parent. Small detached laminae can always be seen through, 

 and are slightly coloured. The fissures in the interior of the 

 crystals sometimes produce a play of colours. 



I have not been able to perceive a double refraction in these 

 crystals. The external planes as well as the cleavage-planes 

 show a glassy and pearly lustre. It scratches fluor spar, and is 

 scratched by felspar. 



According to Brewster, diopside will show signs of electri- 

 city ; but neither by heating nor by rubbing it, have I been 

 able to discover any electricity in this variety. As little does 

 this diopside act on the magnet. Its specific gravity, at 59° 

 Fahr. is = 3*299. A piece strongly striated not belonging 

 to the purest portion, gave at the same temperature a specific 

 gravity of 3*296 ; and one almost white, covered at one end with 

 the above-mentioned bloom, a specific gravity of 3*277. Heated 

 in a platinum spoon, the diopside of Fassa loses its peculiar 

 green colour, but suffers no further change. 



In the flame of the blowpipe, sharp splinters of it are rounded 

 at the edges, but by means only of a very strong heat ; while 

 thick pieces only become of a dirty green colour. With borax 

 it is dissolved very slowly and without colouring the bead. 



Carbonate of soda at a red heat dissolves it with ebullition, 

 and gives a bead of a reddish colour. Phosphate of soda 

 mixed with the mineral in powder, and melted before the 

 blowpipe, yields a dark yellowish bead. On charcoal with 

 nitre it yields a greenish mass, which by further heating as- 

 sumes a dirty reddish colour. Concentrated sulphuric acid, 

 muriatic acid, or nitric acid, does not dissolve the diopside. 



II. Preliminary analytical Experiments. 



A certain quantity of pulverized diopside ignited with thrice 

 the quantity of carbonate of soda freed from water, gave a 

 half-melted mass, which was dissolved in water and muriatic 



acid. 



