122 THE MINERALS OF TASMANIA. 



usual yellow. No analysis has been made as to the con- 

 tained Th O .^. In short, this mineral may be said to occur 

 in almost all the alluvial tin workings, as well as in the 

 vicinity of many of the acid eruptive rocks. The commer- 

 cial supply of monazite, which is remarkably similar to that 

 occurring in this island, is obt'ained from beach workings 

 near Bahia, on the coast of Brazil, and from alluvial 

 workings in North Carolina, U.S.A. 



16. MoNTMORiLLONiTE ( Hydrafed Sdicate of Aliuninium ). 



A soft unctuous clay-like substance, of peach blossom 

 colour. It occurs in the vicinity of Chudleigh. 



217. MoRENOSiTE (Sulphate of Nickel). 



This has occurred in small quantity in one of the old 

 abandoned mine levels at the Blue Tier, near Beaconsfield. 

 It was found in close int'ermixture with other sulphates. 



218. MosANDRiTE ( Titaiio-fluo-silicate of Cerium, Calcium, 



and Sodium). 



An accessory mineral characteristic of the elaeolite or 

 alkaline series of igneous rocks. In writing Mr. W. H. 

 Twelvetrees respecting the garnetiferous mica-solvsbergite 

 of Port Cygnet, Professor Rosenbusch states that under 

 the microscope it was found to contain '' a colourless 

 mineral, in short laths, which, judging from its refraction 

 and double refraction, may possibly be mosandrite." The 

 professor also states, " There is, further, present sporadic- 

 ally, in separate grains, a strongly refractive rusty-brown 

 transparent mineral, which I cannot identify." Referring to 

 a peculiar mica which also occurs in this solvsbergite 

 he remarks that there are " wisps of a peculiar brownish- 

 yellow mica, slightly pleochroic, optically negative, appar- 

 ently uniaxial ; its cross in convergent light does not open 

 out appreciably. This mica takes readily the form of 

 rosettes, which in one place have collected into rectangular 

 aggregates, the outline of which reminds one of the form 

 of amphibole." 



The garnet which is referred to under the name john- 

 stonotite is abundant in this rock, also titaniferous mag- 

 netite, and some pyrites. 



219. Muscovite (Orthosilicate of Fofa.'isium. and Alu- 



minium). 



The common monoclinic white mica, which usually 

 occurs in irregular scales and sheets without any regular 



