462 I. C. Chacko—On Cordierite. 
Cheltenham, and Rugby. The specific gravity is 1:00469. It 
contains in an imperial gallon— 
Carbonate ofiron . - i 3 3 5 traces 
Carbonate of lime . ‘ é : : ‘ 9-743 grains 
Carbonate of magnesia . 2 ‘ 4 2 6-246 ,, 
Carbonate of soda . : é : : : 5-582 25; 
Sulphate ofsoda .  . ; ! Y x 128-989 ,, 
Chloride of sodium . i : : k ; 245-532 —y, 
Chloride of potassium : ; : ‘ ; traces 
Hydrosulphide of sodium i 4 4 : AHI BY | nn 
Iodine and bromine combined . : 2 : traces 
396-366 
The Old Spa on Humberstone Road, near the Wesleyan Chapel, 
derived its reputation from similar Triassic waters. Formerly there 
were salt springs at Weston, near Ingestre in Staffordshire, and brine 
at Branstone, near Burton, but there is no brine in the Leicestershire 
Trias. 
The brine springs at Moira are thought to have derived their 
supply from Triassic beds overlying them. The Ashby baths were 
long noted for the waters procured from this source, and used for 
rheumatism, etc. In this water there is more bromine than in most 
Triassic waters, the springs at Cheltenham yielding 38°65 grains 
per gallon. The Moira brine contains per imperial gallon :— 
Grains. 
Bromide of potassium and magnesium d 0 8-0 
Chloride of sodium . : : A : 5 3700: 
Chloride of calcium . ; : : . : 851-2 
Chloride of magnesium  . ; : : 5 16-0 
Chloride of potassium c ‘ : : : “0 
Iron as protochloride . : : : : 5 trace 
4575-7 
(To be continued.) 
VII.—Opricatty Posrrrve CorDIERITE. 
By I. C. Cuacxo, B.Sc. (Lond.), B.A., A.R.S.M., A.B.C.S. (Lond.), State 
Geologist, Trivandrum, Government of Travancore, South India. 
NORDIERITE was first found in Travancore at Teruwulla (lat. 
() 9° 22’ N. and long. 76° 37’ KE.) in a kind of diorite. In the 
hand-specimen the mineral appears as violet patches and spots. 
Monazite, magnetite or ilmenite, garnet and biotite with probably 
a little hornblende, occur in association with it. In the sections the 
mineral is found to contain numerous globular inclusions which are 
surrounded by pleochroic halos. The larger of these may be identified 
as monazite under the microscope. The mineral is itself pleochroic, 
light vibrating in the direction of the axis of mean velocity 
(Y) showing a pronounced violet tint. When light vibrates in 
other directions the plates do not show any distinct colour, but 
a faint yellow tint may be observed in some plates. When light 
vibrates in the direction of the Y axis the pleochroic halos round the 
inclusions disappear and assume the violet tint of the crystal plate. 
Cordierite is supposed to occur usually in metamorphosed sediments, 
and the pleochroic halos are regarded as due to the presence of 
