160 FIELD COLUMBIAN MusEuM—GEoLocy, VoL. ILI. 
Observed Calculated 
b Ah = (o10) A. (610) = 79 ee i he ghost 
0 A bi se Molo pea = kG ae 56° 3814’ 
DAP = (Id) e Ne Geo) - 43° 73% 48° 44’ 
DOA wl a= (OLo}taetaaa = 45° aay! 45° 22! 
b An = (oro) A (650) = 42 cei 42° 2x’ 
Dy Am =» (O10; A Gio) a Bp epee te 
b Ald ) = ore) Snare oe0) = 20° DRon 26° ast 
bo A fk = oto) eA (i209) = 20° 47/ 20° 48’ 
O° AiO. tie ie OT Clie cree) = 1y° Gs 16° 54’ 
C. Nits = Meola (oree == 24 mies De eat 
Cu /ade see LOOT ew aoa = AI oes 41°20; 
cA Y = (001) A (032) = 53° 5:7 aes 
Caaf. FOOL aes ee = 207 25Gs Cen p ©: 
at i ee Pe hsrenay ts (Cay) a 46° 23" 46° 20’ 
bk @ == {oro} Aer) = 47° 3) Gao 
ON, = a OLS met alae = On 64° 59’ 
Wed eae CA ll (ah X03 )2 7) SGTewr! = go° 20’ go? oo’ 
CoN e 2.9 eet ROO I mel cone == 69? 36" OO (ca. 
RU TICE 
JEQUITINHONHA RIVER, BRAZIL ' 
FIG. I, PLATE LI 
Several crystals of rutile of an interesting habit were presented to 
one of the authors by Olaf E. Ray, Esq., of the Chicago Brazilian 
Diamond Company. The crystals were obtained by Mr. Ray from 
sands washed for diamonds on the Jequitinhonha River near Diam- 
antina, Brazil. The crystals are twins ranging from 9 mm. to 13 
mm. in length and 8 to 1o mm. in width in the direction of one 
lateral axis while in the direction of the other lateral axis their thick- 
ness is only 2 to 3 mm. The crystals have the typical brownish- 
black color of rutile and are practically opaque but occasionally are 
dark-red by transmitted light. The planes are splendent. Exami- 
nation by the reflecting goniometer shows the crystals to be 
made up of the ditetragonal prism h (210) and the pyramid of 
the second order e (101). The development of the planes of the 
pyramid is not uniform, two planes always being larger than 
the other two. The twinning plane is v (301). The prismatic planes 
are frequently striated parallel to the prismatic edges and hence 
