- Email: [email protected]
Origin of South Africa diamonds
I3 °
Notes a n d Comments.
[J. F. I.,
O R I G I N OF S O U T H A F R I C A D I A M O N D S . A n interesting p a p e r on "The D i a m o n d P i p e s and Fissures of South Africa" was recently r e a d b e f o r e the British Association by H . S. I-Iarger. The a u t h o r considers that the age of the Orange R i v e r Colony p i p e s is Triassic (late) or Jurassic, and that the P r e t o r i a p i p e s a r e contemporaneous. "They are," h e said, "the l a t e s t eruptives of South Africa." The origin of the blue g r o u n d in the p i p e s he considers due t o the sheltering of the u l t r a basic rocks, such as eclogite, pyroxenite and lherzolite, all of which a r e commonly m e t with and are made up of the m i n e r a l s which form the bulk of the blue ground. I n t h e s e r o c k s garnet occurs plentifully and also olivine and pyroxene. The d i a m o n d h a s frequently been found crystallized in garnet and more rarely in olivine; h e n c e the gem must have had its genesis in the ultra-basic zone in /vhich t h o s e minerals originated. The experiments of C r o o k e s and M o i s s a n suggest that the p r e s e n c e of iron was necessary f o r the formation of the diamond; but to this Mr. I-Iarger objected, o wi n g to the fact t h a t the necessary iron does not exist in tne d i a m o n d m i n e s and also because Dr. Friedlander's experiments proved that diamonds can be formed in olivine without the e n o r m o u s pressure and h e a t a i m e d at by o t h e r experimentalists. I n conclusion, the a u t h o r expresses the opinion that the deep-seated, ultra-basic zone, in which garnet and ferro-magnesian silicates predominate, was the medium in which t h e crystallization of the d i a m o n d occurred.--Eng, and Min. ]our.
F I R E T E S T S OF W I N D O W G L A S S . Windows and skylights of this material were recently tested at the p l a n t of the British Fire-Prevention Committee. I n the window test five squares of wire glass, 3 ft. 3 in. by 4 ft. 6 in., were set in a brick wall, one in a brick frame, two in s t e e l f r a m e s and t h r e e in brick reveals. The glass was in. thick. The following details are from Engineering News, O c t o b e r 5, I9o5 The first lasted for forty-five minutes, w i t h temperatures r a n g i n g from 650 deg. F. to 1,54o deg. F.; immediately on lighting the gas the glass in all t h e openings cracked, particularly a r o u n d the edges, but beyond the cracks increasing no particular change o c c u r r e d during the firing. The fire did not pass t h r o u g h the glass. O n application of w a t e r t h r o u g h a q - i n . n o z z l e under forty-five pounds per square inch pressure, a n irregular patch of small h o l e s was made in the u p p e r portion of the c e n t e r window, which was also bulged inward; otherwise the glass in all the windows r e m a i n e d in 9osition. I n the skylight tests four squares of glass, about 2 by 2 ft., were placed in the roof of the test house so as to be set horizontally. The fire lasted forty-five m i n u t e s and r e a c h e d a temperature of z,65o deg. F. Immediately o n l i g h t i n g the gas the glass in all four squares cracked in various direct i o n s ; beyond this no perceptible change o c c u r r e d during the fire test. W a t e r was applied to the underside of the glass t h r o u g h h o s e and also p o u r e d on the tops of the glass; its effect was t o develop h a i r cracks all o v e r the glass, but n o w a t e r p a s s e d through.--Iron Age.
Notes a n d Comments.
[J. F. I.,
O R I G I N OF S O U T H A F R I C A D I A M O N D S . A n interesting p a p e r on "The D i a m o n d P i p e s and Fissures of South Africa" was recently r e a d b e f o r e the British Association by H . S. I-Iarger. The a u t h o r considers that the age of the Orange R i v e r Colony p i p e s is Triassic (late) or Jurassic, and that the P r e t o r i a p i p e s a r e contemporaneous. "They are," h e said, "the l a t e s t eruptives of South Africa." The origin of the blue g r o u n d in the p i p e s he considers due t o the sheltering of the u l t r a basic rocks, such as eclogite, pyroxenite and lherzolite, all of which a r e commonly m e t with and are made up of the m i n e r a l s which form the bulk of the blue ground. I n t h e s e r o c k s garnet occurs plentifully and also olivine and pyroxene. The d i a m o n d h a s frequently been found crystallized in garnet and more rarely in olivine; h e n c e the gem must have had its genesis in the ultra-basic zone in /vhich t h o s e minerals originated. The experiments of C r o o k e s and M o i s s a n suggest that the p r e s e n c e of iron was necessary f o r the formation of the diamond; but to this Mr. I-Iarger objected, o wi n g to the fact t h a t the necessary iron does not exist in tne d i a m o n d m i n e s and also because Dr. Friedlander's experiments proved that diamonds can be formed in olivine without the e n o r m o u s pressure and h e a t a i m e d at by o t h e r experimentalists. I n conclusion, the a u t h o r expresses the opinion that the deep-seated, ultra-basic zone, in which garnet and ferro-magnesian silicates predominate, was the medium in which t h e crystallization of the d i a m o n d occurred.--Eng, and Min. ]our.
F I R E T E S T S OF W I N D O W G L A S S . Windows and skylights of this material were recently tested at the p l a n t of the British Fire-Prevention Committee. I n the window test five squares of wire glass, 3 ft. 3 in. by 4 ft. 6 in., were set in a brick wall, one in a brick frame, two in s t e e l f r a m e s and t h r e e in brick reveals. The glass was in. thick. The following details are from Engineering News, O c t o b e r 5, I9o5 The first lasted for forty-five minutes, w i t h temperatures r a n g i n g from 650 deg. F. to 1,54o deg. F.; immediately on lighting the gas the glass in all t h e openings cracked, particularly a r o u n d the edges, but beyond the cracks increasing no particular change o c c u r r e d during the firing. The fire did not pass t h r o u g h the glass. O n application of w a t e r t h r o u g h a q - i n . n o z z l e under forty-five pounds per square inch pressure, a n irregular patch of small h o l e s was made in the u p p e r portion of the c e n t e r window, which was also bulged inward; otherwise the glass in all the windows r e m a i n e d in 9osition. I n the skylight tests four squares of glass, about 2 by 2 ft., were placed in the roof of the test house so as to be set horizontally. The fire lasted forty-five m i n u t e s and r e a c h e d a temperature of z,65o deg. F. Immediately o n l i g h t i n g the gas the glass in all four squares cracked in various direct i o n s ; beyond this no perceptible change o c c u r r e d during the fire test. W a t e r was applied to the underside of the glass t h r o u g h h o s e and also p o u r e d on the tops of the glass; its effect was t o develop h a i r cracks all o v e r the glass, but n o w a t e r p a s s e d through.--Iron Age.