North and South America are hosts to many corundum localities, but very few have produced any significant gems.  The State of Montana is the big exception, and its "Yogo Gulch" sapphires are, from the standpoint of gemology, among the finest in the World.  We shall start with South America (Brazil), then go to Canada, and finally take a look at some of the neatest specimens I have ever seen - from the United States!  As you will see, the Carolinas, California, and Montana all deserve special prominence in any World-wide corundum collection. 
BrazilThough Brazil is noted for other minerals, corundums are fairly rare.
These  rubies (far left) from Serra dos Pombas (Pigeon Mountain), Brumado  and sapphires (near left) from Paraiba do Norte  were saved from the fate of becoming cabochons or beads by the operator of the mines.  Image on right is massive corundum altering to margarite, I think.  
CanadaIn Canada, Ontario in particular is the home to many interesting sub-gem corundum localities.  These specimens are (L to R) are:  bronze corundum (sawn face) from the Craigmont Mine, Burgess County; black corundum from the Robertson-Cooney Farm, Bancroft;
elongated bipyramid with smaller blue corundum crystals from the Gutz Farm, Rosenthal, and an old salmon/green crystal from the Burgess Mine in Carlow.
Here are two unusual Ontario specimens. The Bancroft specimen on the left is a classic (ex coll. D'Agostino), and the main crystal is 3-5/8" long .  The huge (2" by 3-1/2" by 4-1/4" long) bluish green Rosenthal sapphire crystal in matrix on the right was apparently found in 2002.  The last two photos show details of the crystallization.
See the "What's New" page of this website (Item 20) for specimens which we think are from the Yukon Territory.  We are trying to check the provenance; and perhaps you have some helpful information.
Northeastern United States The two specimens on the left are from New Jersey.  The first is a 19th century piece from Newton, and the second is a from a recent Lime Crest Quarry discovery.  The center specimen is a 4" long barrel-shaped crystal from Shimersville, Pennsylvania.  Next is a nodule in mica with a bronze metallic luster from Pelham, Massachusetts; and to the far right is a gemmy wine violet sapphire twin from Warwick, New York.
Southeastern United States:  There is an extensive series of corundum deposits that runs through North and South Carolina into north Georgia.  Below are specimens in the collection from some of the localities.   The left piece is a baseball-sized pink sapphire crystal of uncertain origin (probably, Corundum Hill  - see more on this locality below).
On the right and below are more North Carolina corundums:  detail of sapphire in kyanite from Black Mountain, ruby in fuchsite from Rutherford County, and a rare euhedral prismatic ruby in smaragdite from Chunky Gal Mountain.
In this row, from left to right, are a specimen from the Propst Farm near Maiden or Startown, a cluster extracted during the construction of a dam near Cashiers, a nodule of grey corundum altering to margarite from Lake Chatuge, and a large mass from the Grimshaw Prospect (gift of Burt Kahn).
Left: Cowee Creek and its tributary, Caler Creek, are known for small but fine rubies; often facet grade.  Sapphires (2nd photo) are less common.  Right:  two specimens of pink corundum from Yancey County and Bett's Bridge, Iridell County (gifts of Rob Whaley).  
North Carolina (Franklin):  The Corundum Hill locality, once operated as an emery mine, is perhaps the best known of the regional deposits.  Below are specimens from the collection of the Delaware County Institute of Science collection, apparently all collected during the 19th Century.
South Carolina (York County): 
The Rickard Mine, a few miles south of Charlotte, North Carolina, was once a commercial emery mine.  It still produces attractive nodules and fragments of black corundum.  Our finest (far left) is a gift of Rob Whaley.  The others were self-collected in May, 2003..
South Carolina (Cherokee County):  A would-be colleague from Cowpens found large chunks of material which, from their appearance in photos, are probably corundum but resemble boat anchors.  Look for pictures of donations in this space soon (one, "Kermit", is green).  A site visit in May, 2003 produced some tiny float corundum crystals, but the big ones may be another type of rock - samples are being sent for analysis.  Stay tuned.
South Carolina (Laurens County):
Laurens is known for its mica-coated "rat tail corundum" (far left), but here are also a prismatic crystal  (note bluish color in terminal face) and a small twin.  On the right is a 19th Century crystal of dark green corundum from Laurens Courthouse.
Idaho:  The State of Idaho possesses a lot more than just potatoes and those nasty yellow "epoxy beetles" you can't even scrape off your windshield!  The specimens below are from the vicinity of McCall.  The double fist matrix specimen in the center (detail shown) is a gift of Terry Maple, Marysville, Washington.
Wyoming:  Thin slabs of these ruby nodules in amphibolite matrix from the Rattlesnake Mountains are translucent, and have been made into lamp shades and wind chimes.  
ColoradoThe Turrett Mining District, Chaffee County produces small grey corundum crystals in chlorite/schist mtrix.  This is a detail from a specimen about 5" in diameter; the crystals are to about 3/4" long.  
California (Mount san Jacinto):  A recent discovery by two brothers, Ken and Dana Gochenour, created a stir when their specimens were displayed in coastal mineral shows.  These opaque, brownish grey bipyramidal crystals are unusual not only because of their size (the longest found is about 9'1/2"  - see right) but also because of their unfortunate habit of being found in sections which have to be extricated from the host rock and reassembled (see below, left)!  The result of the Gochenours' careful preparations can be striking!
Montana: The rest of this page is devoted to corundum deposits in the State of Montana.  There are sub-gem occurrences in a zone that runs more or less from Bozeman to Dillon, and at least three regional deposits of gem sapphires, which we shall call the Missouri River, Skalkaho, and Yogo Gulch deposits.
Montana (Bozeman - Dillon):  Most of the material from this series of deposits is sub-gem, but it often occurs in euhedral crystals and clusters. 
     Current research is being conducted by Dick Berg, Senior Research Geologist, Montana Bureau of Mines and Geology, who doubles as Curator of the Mineral Museum at Montana Tech in Butte.  He and I hope to do some field work together and compare notes and specimens in the summer of 2004.  I am greatly indebted to Dick, who donated the specimens on the left below  to the collection.  See also his outstanding SEM's (scanning electron micrographs) of gem Montana sapphires on the "Micro" page.
      Far left is from Elk Creek, other is from Camp Creek.  On the right are specimens from the BLM Shaft in the Bozeman area (Gallatin County).  The second shows crystals of the micromineral "baddeleyite" (zirconium oxide).  
Montana (Missouri River):  The Missouri River Bars (not the ones closed on Sundays) in the vicinity of Helena contain millions of carats of pastel gem sapphires.  In the past, these have been mined for gemstones, instrument bearings, and to a small degree, abrasives.  Mining the tourists and artisans also became a prominent activity, as numerous day digging sites sprang up.  However, the future of these activities is uncertain, as their popularity in jewelry and industrial uses have waned and unfortunate business practices have muddied the waters.
A trip to Montana is planned for July, 2003, during which I hope to ascertain the latest status of these operations and report back to you in a paper, "Corundums of Montana".  Here are some photos of Missouri River specimens in the collection, including a very rare white sapphire in matrix (self-collected from a proprietary location).
Montana (Skalkaho):   These deposits include the classic "Gem Mountain" and other Rock Creek deposits, Dry Cottonwood Creek, Pole Creek, and other minor occurrences in the general area between Plillipsburg and Hamilton
On the left are small but superb crystals, respectively from Dry Cottonwood Creek and Rock Creek, given by Marc Bielenberg to Louis Zara.  On the right are a doubly terminated "hot pink" crystal given to me by Ben Duffey and a typical small "mine run" lot. Both are from Gem Mountain.
Montana (Yogo Gulch):  Located at the geometric center of the state, Yogo Gulch is a source of some of the World's most nearly flawless "cornflower blue" sapphires.  The bad news is that they tend to be very small.  Faceted stones over one carat are somewhat rare, and you can pretty much forget about one over three carats!  A very small portion of the stones have varying degrees of a reddish hue, and are called "violet sapphires".
      The crystal on the left is a "flawless" 6.16 carat Yogo sapphire, an example of the finest cutter the mine produces.  Most of the specimens are flat and do not give good weight retention, as is this outrageous 6.62 carat specimen (near right).  The 3.35 carat violet crystal (far right) may be the best of this color ever found.    
    Below are some pictures of blue and violet rough; faceted stone (3.60 ct.) and jewelry piece (stone 3.20 ct.); a neat "frisbee" 3.35 ct. crystal; Vortex Mining wash plant;
the troll at the entrance to the mine; and in the last picture, our way of saying:  "Have a Nice Day!!"  
Storage Bin:
(1)  Montana , vic. Helena (French Bar?);       (2)  Detail of white corundum in schorl (black tourmaline), Cherokee County, South Carolina;    (3) Gem ruby termination, Grimshaw Prospect, Transylvania County, North Carolina;  

(4) Massive corundum, Cherokee County, South Carolina.   (5) and (6) my two favorite violet Yogo sapphire crystals .

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