Augite of Haleakala, Hawaiian^ 



Analyses of augites from basalts 



1 2 



SiO., 47.70 47.06 50.0 



A1 2 3 6.82 7.77 3.71 



Fe.0 3 3.36 1.30 



Feb 4.43 8.15 



M^O 13.34 13.52 



CaO 21.35 19.33 



Na,0 0.65 0.33 



K,0 0.03 0.11 



HoO+ 0.15 0.20 



Tib, 1.89 1.82 



Cr,6 3 0.23 trace 



MiiO 0.16 0.20 



Densitv . 



100.11 

 3.358 



99.85 



1.47 



2.05 



4.96 



7.41 



14.01 



14.59 



22.48 



20.34 



0.73 



0.61 



0.01 



0.18 



0.22 



0.08 



2.11 



0.96 



n.d. 



n.d. 



0.21 



0.10 



100.00 



100.71 



3.366 



3.236 



4. 



Augite, near Eed Hill, Haleakala, Maui, Hawaiian Islands, Washington 

 analyst. 



Augite, near Grant's, Mount Taylor Region, New Mexico, Chatard 

 analyst. J. S. Diller, TJ. S. Geol. Survey, Bull. 591, p. 149, 1915. 



Augite, Monti Bossi, Eruption of 1669, Etna, Sicily, Washington analyst. 

 Washington and Merwin, this Journal, 1, 29, 1921. Corrected for 4 

 per cent of magnetite. 



Augite, II Liscione, Stromboli. Washington analyst, Kozu and Wash- 

 ington, this Journal, 45, 467, 1918. Contains 0.08 SrO. 



"When we attempt the interpretation of the analysis in 

 terms of mineral molecules we are confronted with the 

 question of the disposition of the sesquioxides, that is, 

 the alumina and ferric oxide above the amounts needed to 

 form acmite or possibly jadeite molecules. This is the 

 crux in the interpretation of all aluminous augites, and it 

 is usually met, it is scarcely necessary to say, by the 

 assumption of the existence of the so-called Tschermak 

 molecule (Mg, Fe)0.(Al, Fe) 2 3 .Si0 2 . This is not the 

 place for a proper discussion of this vexed matter, which 

 must be postponed to a later occasion when the general 

 subject of the composition of the pyroxenes is taken up. 

 It may, however, be said here that our studies so far have 

 led us to disbelief in the existence of the Tschermak mole- 

 cule, a conclusion in which we are at one with Boeke 5 and 

 Zambonini. 6 We cannot, however, agree with Boeke 's 

 conclusion that "the aluminous monoclinic augite is 



5 H. E. Boeke, Zs. Krvst., 53, 445, 1914. 



6 F. Zambonini, Atti Ace. Sci. Napoli, 16, No. 2, p. 9, 1914. 



