126 



bowralite by Mr. Mawson, B.Sc, B.EJi^) Here we have in 

 the Houghton rocks, occurring in small lenses in the main 

 intrusion, a type of pegmatite which has the chief character- 

 istics of the Houghton intrusive, i.e., high titanium content^ 

 acid plagioclase, original presence of diopside (now actinolite), 

 and considerable apatite. For this pegmatite the name yatal- 

 ite.has been suggested. (See plate iv., fig. 11.) 



Fig. 3. — Key to photograph, plate iv.. fig. 11, of a specimen of 



Yatalite. 



Yatalite is a coarse-grained pegmatite, composed of 

 uralitic actinolite (after diopside), albite containing micro- 

 cline, titaniferous magnetite, sphene, and quartz. The actin- 

 olite is the predominant mineral, occurring in large subidio- 

 morphic paramorphs after diopside, poikilitically including 

 the magnetite and sjDhene. Magnetite, rather less abundant, 

 occurs in large crystals and smaller grains ; albite is in large 

 idiomorphic crystals, sphene and apatite are less important, 

 and quartz occurs interstitially. The mineralogical features 

 of each of these components have been described above (pp.- 

 110 ct scriq.). 



(i8)Proc. Linn. Soc, X.S.W., 190G, p. 



606. 



