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The greatest gem mine in the world
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~Voles alzd CoJJzmelcts. THE GREATEST
[J. F. I.,
GEM MINE IN THE WORLD.
The sapptlire w o r k i n g s at Y o g o Gulch, M o n t a n a , are being gradually developed into a great and p e r m a n e n t m i n i n g industry, says Mr. G e o r g e F. Kunz in a forthconfing r e p o r t on precious stones, published by the U n i t e d States Geological Survey. T a k e n as a whole, the Y o g o dike is perhaps the g r e a t e s t gem mine in the world. It is a~oout 4 miles long on the surface, and b e i n g a true igneous dike, descends to an indefinite depth. It is estimated t h a t the entire c o n t e n t of workable s a p p h i r e - b e a r i n g rock would a p p r o x i m a t e io,ooo.ooo cubic yards. A m i n i n g plant is n o w b e i n g erected here which will quadruple the previous output and make M o n t a n a sapphire m i n i n g a very i m p o r t a n t factor in A m e r i c a n gem production. The stones obtained are not of large size. They r a n g e from "culls," used for watch jewels and o t h e r mechanical p u r p o s ~ o gems averaging, when cut, f r o m half a carat to 2 or 3 carats and rar/~le up to 5 or 6. As gems they are brilliant, free from flaws and o{ good color, r a n g i n g from light shades to the rich, deep blue of oriental sapphires. T h e Y o g o crystals have an advantage for mechanical uses over East Indian s t o n e s in their form. which is largely short prismatic or r h o m b o h e d r a l with flat basal t e r m i n a t i o n s , and hence they need much less cutting for such purposes as w a t c h jewels. T h e gems are sent to A m s t e r d a m for cutting, and yield from tw0-fifths to one-half t h a t weight of finished stones.
ABRASIVE
MATERIALS.
The U n i t e d States Geological Survey is about to publish its annual rept>rt on the production of abrasive materials during I9o 5. The r e p o r t takes note onIy of that small part of the production of these materials which is actually used for abrasive purposes. The a g g r e g a t e value of the p r o d u c t i o n of the natural abrasive m a t e r i a l s (luring 19o5 was $1,427,78o, which is an increase of $2o,679, as c o m p a r e d with $1.4o7,1Ol. the value of the z9o4 production. This includes oilstones and scythestones at $244.346, g r i n d s t o n e s and pulpstones at $777,6o6, b u h r stone~ and millstoi~es at $37,974, pumice at $5,54o. infusorial earth and tripoli at $64,637, crystalline quartz, including feldspar, at $88,II8, g a r n e t at $[48.o~95. and c o r u n d u m and emery at $6],464. There is considerable v a r i a t i o n from year to year in the value of the different abrasive materials, and this r e p r e s e n t s in nearly all cases a corresponding variation in the quantity produced. As a rule, however, the actual q u a n t i t y of abrasive materials produced and put on the m a r k e t in one year is increasing. The value of the artificial abrasive m a t e r i a l s - - s u c h as c a r b o r u n d u m , crushed steel, and a l u n d u m - - m a n u f a c t u r e d during 19o5 is estimated at $7oi,4oo, as c o m p a r e d with the estimated value of $83o,926 of the 19o4 production, a decrease of $I29,526. This, however, is a large increase as compared with $493,815 in 19o3, and with $390,245 in 19o2. The r e p o r t was prepared by Mr. J o s e p h H y d e Pratt.
~Voles alzd CoJJzmelcts. THE GREATEST
[J. F. I.,
GEM MINE IN THE WORLD.
The sapptlire w o r k i n g s at Y o g o Gulch, M o n t a n a , are being gradually developed into a great and p e r m a n e n t m i n i n g industry, says Mr. G e o r g e F. Kunz in a forthconfing r e p o r t on precious stones, published by the U n i t e d States Geological Survey. T a k e n as a whole, the Y o g o dike is perhaps the g r e a t e s t gem mine in the world. It is a~oout 4 miles long on the surface, and b e i n g a true igneous dike, descends to an indefinite depth. It is estimated t h a t the entire c o n t e n t of workable s a p p h i r e - b e a r i n g rock would a p p r o x i m a t e io,ooo.ooo cubic yards. A m i n i n g plant is n o w b e i n g erected here which will quadruple the previous output and make M o n t a n a sapphire m i n i n g a very i m p o r t a n t factor in A m e r i c a n gem production. The stones obtained are not of large size. They r a n g e from "culls," used for watch jewels and o t h e r mechanical p u r p o s ~ o gems averaging, when cut, f r o m half a carat to 2 or 3 carats and rar/~le up to 5 or 6. As gems they are brilliant, free from flaws and o{ good color, r a n g i n g from light shades to the rich, deep blue of oriental sapphires. T h e Y o g o crystals have an advantage for mechanical uses over East Indian s t o n e s in their form. which is largely short prismatic or r h o m b o h e d r a l with flat basal t e r m i n a t i o n s , and hence they need much less cutting for such purposes as w a t c h jewels. T h e gems are sent to A m s t e r d a m for cutting, and yield from tw0-fifths to one-half t h a t weight of finished stones.
ABRASIVE
MATERIALS.
The U n i t e d States Geological Survey is about to publish its annual rept>rt on the production of abrasive materials during I9o 5. The r e p o r t takes note onIy of that small part of the production of these materials which is actually used for abrasive purposes. The a g g r e g a t e value of the p r o d u c t i o n of the natural abrasive m a t e r i a l s (luring 19o5 was $1,427,78o, which is an increase of $2o,679, as c o m p a r e d with $1.4o7,1Ol. the value of the z9o4 production. This includes oilstones and scythestones at $244.346, g r i n d s t o n e s and pulpstones at $777,6o6, b u h r stone~ and millstoi~es at $37,974, pumice at $5,54o. infusorial earth and tripoli at $64,637, crystalline quartz, including feldspar, at $88,II8, g a r n e t at $[48.o~95. and c o r u n d u m and emery at $6],464. There is considerable v a r i a t i o n from year to year in the value of the different abrasive materials, and this r e p r e s e n t s in nearly all cases a corresponding variation in the quantity produced. As a rule, however, the actual q u a n t i t y of abrasive materials produced and put on the m a r k e t in one year is increasing. The value of the artificial abrasive m a t e r i a l s - - s u c h as c a r b o r u n d u m , crushed steel, and a l u n d u m - - m a n u f a c t u r e d during 19o5 is estimated at $7oi,4oo, as c o m p a r e d with the estimated value of $83o,926 of the 19o4 production, a decrease of $I29,526. This, however, is a large increase as compared with $493,815 in 19o3, and with $390,245 in 19o2. The r e p o r t was prepared by Mr. J o s e p h H y d e Pratt.