132 



produced by its refinement, with their approximate values. A 

 large specimen of native sulphur, formed during a recent erup- 

 tion of Tarawera (New Zealand), is also placed here. In case 

 91 will be found crystallised (9450) and massive varieties (735) 

 from Sicily, massive from Eiissia, siliceous from Utah (3557), 

 and auriferous (2 dwt. per ton) from Colorado (3556). 



Much of the sulphur of commerce is obtained by the roasting 

 of pyrites ores. In case 122 will be found a small scries from 

 Spain, showing copper-pyrites ore, with the products resulting 

 from its treatment. — metallic copper, slag-wool, crude sulphur, 

 refined sul phur (" flowers ' ' and "rolled ") , and bluestone (sulphate 

 of copper). 



Cases Mica as a rock-forming mineral is referred to on page 



141, 105, lis. When obtainable in large, thin sheets, mica is of great 

 Mica. value, being used in electrical and other work. The scrap mica 



from the mines is used up in a great variety of ways. It has 

 been found of commercial quality in the Macdonnell Eanges in 

 Central Australia, and possibly one or two other places but is only 

 mined at the former locality in Australia. Good specimens, 

 in small sheets, are shown from West Australia, including the 

 lithium variety from Coolgardie (seepage 148). 



The mica of commerce comes principally from Canada and 

 India ; and, in addition to these countries, from the United States 

 (Idaho and South Dakota). 



Case 141. "Asbestos" refers in commerce to certain minerals that are 

 Asbestos sufficiently fibrous, tough, and flexible to admit of being 



woven. Varieties of hornblende and of serpentine both fulfil 

 those conditions, and both are included under " asbestos." 

 The most valuable property possessed by asbestos is its com- 

 parative indestructibility by fire, although different samples vary 

 considerably in this respect. Many samples which appear good 

 to the eye may be found, when submitted to practical tests, to be 

 deficient in some quality — very commonly in toughness. 



