FRA N:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 85 
northern part of the amphibole-malignite. All around are 
— schistose rocks of the Coutchiching series. The mode of 
occurrence is not unlike that of the sviatonossite, though 
little can be said about the latter, the observations being 
scanty. 
Turning to the following group of rocks to be compared 
with the sviatonossites, viz. the borolanites of Cnoc-na-Sroine 
near Loch Borolan in Scotland, we must-begin with a state- 
ment about their mode of occurrence 1). This is very char- 
acteristically laccolithic, the borolanites forming part of a 
larger mass measuring »4 miles by 2.5 miles in outcrop, 
with a probable original thickness of about 0.25 mile». The 
upper part is made up of quartz-syenites passing down wards 
through a quartz-free syenite into the garnet-bearing varie- 
ties. Among these are many different types, signified with 
several names. The chief types are borolanite (analy- 
sis X) and le dm orit e (analysis IX). The former is defined 
by Horne and Teall as follows: »The typical rock is a crystal- 
line granular aggregate of orthoclase and melanite. Biotite, 
pyroxene, alteration products after nephelite and sodalite, 
 sphene and apatite occur as subordinate and variable con- 
ri. 
Fal 
stituents». Ledmorite is defined as a variety or sub-group 
of the borolanite containing aegirite-augite in addition to 
(and replacing) melanite. This is often associated with peg- 
matitic modifications. Varieties containing less than about 
10 percent by volume of melanite have been termed m el a- 
nite-syenite (analysis VII. Assyntite (analysis 
- VIII) is a dike-rock consisting of aegirite-augite, orthoclase 
and feldspathoids. | 
Mineralogical analogy between the borolanite series and 
the sviatonossites is very close. The potash feldspar in the 
borolanite rocks is orthoclase-microperthite and the plagio- 
clase when present has been determined by Shand as oligo- 
1) The Borolan laccolith has first been described by J. Horne and J. J. 
Teall, »On Borolanite>, Transact. of the Royal Soc. of Edinburgh, Vol. 
XXXVII, 1892. The last and most complete report is: S. J. Shand, »On 
— Borolanite and its Associates in Assynt>, Transact. Edinburgh Geol. Soc. 
Vol. IX (1910). 
