August 1, 1864] THE TECHNOLOGIST. 



WHAT PRECIOUS STONES ARE MADE OF. 41 



copper ; and lapis lazuli is only a bit of earth painted throughout with 

 sulphuret of sodium. 



The sapphire is one of the most precious stones, and inferior only to 

 the diamond in hardness, the diamond being the hardest substance in 

 nature. 



It is of a very extensive suite of colours, passing from pure white to 

 deep blue, to red, to yellow. Each variety bears a different name ; thus 

 the blue variety is called sapphire, the crimson-red variety is ruby, the 

 yellow oriental topaz. The foregoing colours occur from the palest to 

 the deepest hue. The pure white is called Lux Sapphire. The violet- 

 blue variety is occasioned by the blending of the red and blue colours 

 in the same stone : it is generally called violet ruby. The sapphire is 

 sometimes met with of a green colour and of a bluish grey, and of every 

 modification of these principal colours pure and mixed, transparent and 

 opidescent. In some specimens two colours occur in the same stone, as 

 blue and red, white and blue. 



The finest specimens of these stones are procured from Pegu, iu Asia. 

 From Ceylon the sapphire is very inferior in colour, being pale or 

 streaked, the ruby being of a port-wine tint, whereas from Pegu the 

 colour is of crimson or blood-red. It is also found in various parts of 

 Europe, but of a very inferior quality. It is generally found in alluvial 

 soil in the vicinity of the secondary or trap formation, also imbedded in 

 gneiss, and in iron sand, with fragments of pirope and zircon. 



Its primitive form is a six-sided pyramid, or a short six-sided prism ; 

 the red or ruby occurs generally in blunt-edged, rounded, or rhomboiclal 

 grains ; the blue or true sapphire is much oftener of the regular form of 

 the pyramid and prism. Its specific gravity is from 4. to 4-2. It is 

 composed chiefly of crystallized alumina (i. e., pure clay), its component 

 parts being alumina, 92. ; silex, 55 ; oxide of iron, lime, &c, 2 - 5. 



The value of these stones depends entirely upon the depth of colour 

 and size. The ruby is very highly prized when of a fine colour, but it 

 is never found of a large size. The sapphire is often found very large, 

 but fine colour is very rare. There is also another description of sapphire 

 and ruby having an opalescence at one end ; these stones, when cut 

 elliptical in form, keeping the opalescence over the apex, produce the 

 appearance of a star with six rays : these are called asteria or star stones, 

 and are highly prized. Many of this description have been found in 

 Australia, as well as several specimens of transparent sapphires of good 

 quality ; it is therefore probable that specimens of all the varieties of 

 colour abound in the colony, and might be discovered by any com- 

 petent person acquainted with this gem, and prove to be highly 

 remunerative. 



If any doubt existed on the subject of Australia being a diamond- 

 producing country, it is now removed. A successful digger named 

 Williams, from the Yackandandah district, submitted to Mr. Crisp, 

 jeweller, Queen Street, a collection of small stones which he had picked 

 vol. v. G 



