ff.S. 



Washingt 



on — £ 



Mvsbei 



yite 



and Tinguaite. 



185 





I. 



II. 



in. 



IV. 



V. 



VI. 



VII. 



VIII. 



Si0 2 



5675 



56-58 



55-65 



53-21 



54-07 



54.46 



58-70 



58-64 



Ti0 2 



Zr0 2 



AlaOs 



0-30 



.... 



.... 



0-35 



015 



trace 



trace 



0-20 



0-09 



19 62 



20-69 



19-89 

 3-18 

 0-56 



20-06 

 3'45 ) 

 J-25 j 



2~2~02 

 4-1S 



21-67 

 355 



19-96 

 234 

 333 



19-26 

 3-37 

 0-58 



Fe 2 3 



3-52 



2-17 



FeO 



0-59 



0-42 



MnO 



trace 



0-47 







0-42 







trace 



o-io 



0-20 



MgO 



0-11 



013 



0-78 



0-91 



0.36 



0-61 



0-76 



0-37 



CaO 



0-37 



110 



1-45 



1-33 



0-36 



2'12 



1-41 



1-24 



BaO 



none 



























trace 



SrO... 

























trace 



NaoO 



1145 



10-72 



899 



1037 



8 91 



8-68 



8-55 



8-39 



K 2 



2-90 



5-43 



6 07 



6-41 



4-76 



2-76 



4-53 

 0-07 



5-26 



H 2 O110°-.__. 



0-04- 



0-34 



HoO 110° + 



3-18 



1-77 



1-51 



0-81 



5-44 



5-20 



2-57 



o-io 



240 



P 2 5 





0-03 



S0 3 



























trace 



CI 



0-28 



























0.14 



co 2 































23 



9992 99-83 99-21 100 01 9927 99 46 100-0 99'74 



I. Tinguaite, Pickard's Point, Manchester, Mass. H. S. Washington, anal. 



II. Tinguaite (dike border), Hedrum, Norway, Brogger, Gror. TiDg. Ser. 113. 

 G. Pajkull, anal. 



III. Tinguaite (dike center), Hedrum, Norway, Brogger, Gror. Ting. Ser. 191. 

 V. Schmelck, anal. 



IV.' Tinguaite Porphyry, Foia, Serra de Mouchique, Portugal, Kraatz-Koschlau 

 and Hackman, Tsch. Min. Pet. Mitth., xvi, 257, 1896. Mean of three poor 

 analyses by students of Jannasch. 



V. " Aegirite Tinguaite," Hot Springs, Ark., J. F. Williams, Ark. Gool. Surv., 

 1890, ii, 370. W. A. Noyes, anal. 



VI. Tinguaite, Njurjawpachk. Umptek. Kola, Ramsay and Hackmann, Neph. 

 Sven. Geb. Kola, Fennia 11. No. 2, 158, 1894. K. Kjellin, anal. 



VII. " Acmite Trachyte," Crazy Mts., Mont., Wolff and Tarr, Bull. Mus. Comp. 

 Zool., xvi, 232, 1893. W. H. Melville, anal. 



VIII. Phonolite, Cripple Creek, Colorado, 16 Ann. Rep. U. S. G. S., ii, 39, 1895. 

 W. F. Hillebrand, anal. 



The rock which approaches closest to it is the tinguaite from 

 the dike border at Hedrum, Norway (No. 2), the two being 

 almost identical, except in K 2 and H 2 0. Its relations to 

 other tinguaites may be seen in the table, from which those 

 very rich in potash are excluded. 



The calculation of the mineralogical composition is some- 

 what uncertain, owing to the presence of three soda-alumina 

 silicates, nepheline, aibite and analcite, and ignorance of what 

 amount of the H 2 present really belongs to the last. An 

 attempt has been made in No. I<2, which, though only very 

 roughly approximate, corresponds fairly well with the rock as 

 seen in thin sections. This calculation was subsequently 

 checked by determination of the portion of the rock soluble 

 in dilute HC1. The soluble portion amounted to 49*24 per 

 cent of the whole. As the amount of nepheline and analcite 

 was calculated to be jointly 483 per cent, and as a very small 



Am. Jour. Sol— Fourth Series, Vol. VI, No. 32.— August, 1898. 

 13 



