So:^IE KvAXJTK-IJKAKIXG KOCKW FRO-M tbe Kasterk Goldfiflds 
Westerx Australia. 
13 
^ B 
1 MM 
I 
Fig. 3. 
A. j\ y;iuit<^-(|u;irtz .schist (suvciiiieu L3117) from tlio (’anu‘l Hiiiniis. Showing- 
('harnct(M-istio hlnded form of kyaiiite cut parallel to (100) (clear 
(u-ystai). Rutile inclusions in clustered aggregate (black). 
B. Tlio same, with kyanite crystal showing perfect (100) deuvage and imiDerfect 
(010) fi‘()SK-]>arting in section cut ap])roxiinatcly parallel to (001). Note 
diablastic iiitcrgrowtli of granular kyanite witli quartz matrix. 
The following optical }n'operti(‘S have been determined:— 
The optica] elongation is i)ositive. Z A c is 29°-3()° on sections cut 
l)arallel to (100). 
The mineral is biaxial with negative optical character. 
Optical axial plane is approximately normal lo (100) and inclijied at 
29°-30° to e-axis. 
2V is large ( 80'^). 
The refracti^’(‘ indices are: — 
a = 
1-711 h 
- 
1-718 
^ F 002 
r ^ 
1-728 J 
7 — 
» = -015 
± -002 
Twinning, oft(m a characteristic feature of this mineral, was only 
occasionally noticed on (100) as twin |>laue. Micrometilc observations in- 
dicate the presence of 15% to 25% of kyanite in this rock. Inclusions in 
these kyanite pon)iiyrol)la.sts (A)nsist of ((uartz grains, clustei's of y'ellow 
rutile prisms and occasonal detrital zircons. 
The quartz matrix enclosing the kyanite consists of a tiiu‘ grained, even- 
grannlar mosaic of crystals averaging about .04-. 08 mms. in diameter, in- 
cluded in and surrounding the broken grains of kyanite. 
(Quartz and kyanite constitute the essential minerals in this rock. 
