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A N:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 83 
The three types of malignite from Poohbah Lake are 
rather different in their mineral composition as appears from 
their names, orthoclase being the chief felsic constituent in 
all the types. Chemically, however, the same characters are 
well marked in all: they are rich in lime as well as in alkalies. 
In I and III ferrous oxide and magnesia are presentin a quan- 
 tity just sufficient to form diopside with the femic lime — 
and almost all the lime is femic in the malignites. In the 
garnet-pyroxene-malignite which has the closest resemblance 
to the sviatonossites the femic lime in proportion to (Fe, 
Myg)O is in large excess over the diopside ratio and much 
normative wollastonite is found, actually entering into the 
andradite. Thereby the percentage of soda is high enough 
to exceed the molecular quantity of alumina remaining when 
the potash present has been exhausted-to form orthoclase, 
and acmite must be introduced in the norm. This normative 
composition agrees fairly well with the qualitative modal 
composition of this rock according to Lawson. We may 
briefly quote the most essential characteristics of the garnet- 
pyroxene-malignite: The constituent minerals are: ortho- 
clase with which nearly pure albite occurs in microperthitic 
intergrowth, forming huge, thick plates embedded in a dark 
green, moderately fine-grained holocrystalline matrix. The 
latter is a »hypidiomorphic granular aggregate of aegirite- 
augite, melanite, biotite, titanite and apatite, stated in the 
order of their abundance, together with a subordinate pro- 
portion of microperthite and albite». One cannot fail from 
these characters to find this malignite to be mineralogically 
nearly identical with some of the sviatonossites. Certainly 
the minerals are the same in both except that biotite has 
been observed in the sviatonossites merely in traces. The 
garnet is said to be free from inclusions. As the titanite, in 
euhedral crystals, is stated to be abundant and the percentage 
of TiO, in the rock is only 0.33, the garnet, being reddish 
brown to yellowish in colour, must be very poor in titanium, 
sharing this property with the garnet from the sviatonossite 
as well as with the skarn-andradites. Some difference bet- 
ween the malignite and the sviatonossite may be found in the 
