MR. T. H. HOLLAND ON ROCK-SPECIMENS FROM KOREA. 1 91 



I. 



Silica 49-62 



Alumina 28*72 



Feme Oxide 12-86 



Manganese Oxide 1*51 



Lime 0-23 



Magnesia 8-6-1 



Water (loss) 



II. 



III. 



IV. 



49-17 



48-15 



50-41 



33-10 



32-50 



32-95 



4-82 



8-80 



1-07 



0-04 



0-28 



1-12 



11-45 



10-14 



12-76 



1-20 



0-50 



1-02 



101-58 99-78 100-37 99-36 



I. From Haddam, Connecticut (specific gravity 2-65). Thomson, 



Dana's " Syst. Min." 1st ed. p. 278. 



II. From Simiutak, Greenland (specific gravity 2-59). Stromeyer, 



" Untersuch. iiber die Misch. der Min." &c., Gcittingen, 1821, 

 pp. 329 and 431. 



III. From Unity, JSTew Hampshire. C. T. Jackson, " Geol. Kep. of 

 N. Hampshire," p. 184. 



TV. From Krageroe, Norway. Scheerer, Pogg. Ann. vol. Ixviii. 

 p. 319. (Mean of two analyses of pale-blue variety.) 



Dichroite was found by Dr. Gottsche in a garnet- gneiss from 

 Songchang, 40 U east of Wiwon, Phyong-an Do. Other accessories, 

 like magnetite, pyrite, talc, chlorite, and, perhaps, tourmaline and 

 topaz, I have noticed in various specimens. Different forms of 

 gneisses are obtained depending on the variability in relative pro- 

 portions of these constituents. These rocks are found extending 

 sometimes for many miles building up the low rounded hills which 

 characterize Korean scenery in the central and southern provinces, 

 and decomposing into a soil on which rice is extensively cultivated 

 in the valleys and on the plains. 



About 18 li south-east of Chhungju, in the province of Chhung- 

 chhong, Mr. Gowland collected specimens of a true hornblende- 

 schist, consisting almost wholly of green fibrous crystals of horn- 

 blende with secondary quartz formed around the actinolitic crystals, 

 and with occasional patches of graphite and minute magnetite. In 

 the section are to be seen the results of yielding to stresses across 

 the lines of schistosity in the faulting of the hornblende crystals, 

 accompanied by a frequent bending of the fibres near the fault-line. 

 The cracks have been infilled with a detritus of smashed hornblende- 

 crystals, and sealed with secondary quartz and minute plagioclase- 

 felspars. Hornblende-schists were found by Dr. Gottsche in Chol-la 

 Do and in Phyong-an Do. 



A minutely puckered quartz-mica-schist was obtained by Mr. Gow- 

 land between Chhun^u and Brambe. The quartz occurs in small 

 granules with white mica and, less abundantly, pleochroic brown 

 mica, the latter often changing to a green. Tourmaline and mag- 

 netite are also present. Occasional bands or len tides of calcite 

 occur, with the granular crystals exhibiting distinct twin-structures. 

 Veins of carbonate of lime occur in this and the neighbouring rocks. 



o2 



