Updated February,22, 2015

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Updated July 22nd, 2001

What's New at the Mine

In 2000 Benitoite Mining, Inc. (BMI), of Golden, Colorado negotiated a deal to purchase the mine from owners Bill Forrest and E. Buzz Gray.  During the spring and summer of 2001 BMI engaged exploration andin mining activities to recover specimens and gem rough of benitoite.  Their efforts met with success as they recovered several hundred specimens of rough and specimen grade benitoite/neptunite.   They uncovered extensions of the original vein that was offset and down dropped by a fault.  It was also covered by 10 meters of colluvium. Specimens were found in situ and during excavation.

The photos below display one of the new large blocks recovered and the techniques used to recover benitoite.

Photo courtesy of Benitoite Mining, Inc.

The excavator was used to remove the overburden covering the offset vein structure.  Large boulders with obvious benitoite and/or neptunite mineralization are stockpiled as the digging proceeds.

Photo courtesy of Benitoite Mining, Inc.

The above is very typical of specimens as they are found at the mine,  Note the contact between the blue schist and the white natrolite.  You can plainly see crystals of neptunite along the edge.  This is an obvious indicator of a strong possibility for more crystals once the natrolite is removed.  On pieces like this the presence of bumps also strongly suggest benitoite and neptunite crystals underneath. 

Photos courtesy of Benitoite Mining, Inc.

Water is sprayed over a jig to help remove the tenacious clay that sticks to everything and everyone that it comes into contact with.  Only during the spring and early summer is enough water available to facilitate mining.  During the summer months the water supply dries up and during the winter months the mine location frequently becomes a winter wonderland of snow and ice.

Photos courtesy of Benitoite Mining, Inc.

Small pieces of rock potentially containing benitoite are run through a sluice-like device (shown above).  Benitoite, being dense is trapped in the riffles of the sluice.  The sluice is, also, filled with steel shot.  The steel shot is used as a density agent to bring the less dense material (benitoite) to the surface of the sluice for hand picking of gem rough. Note the crystal in the right hand photo...

Photos courtesy of Benitoite Mining, Inc.

One of the large boulders found this past June.  The close up photo displays several of the numerous veins exposed which have shows of benitoite and neptunite.  What a GREAT rock!

The value of benitoite in gem and specimen grades has risen steadily over the years as its popularity has grown.  It is expected to continue to rise into the future since the supply will always be limited.   Bryan Lees, of CEMI, is optimistic about future prospects for specimen and gem rough production from the Benitoite Gem Mine.    CEMI intends to make mineral specimens and gemstones available as long as raw material is available to be processed.    Speaking of processing, there is a substantial cost of time and expertise that goes into the cleaning and preparation of specimens.   The cost of a benitoite specimen reflects this effort in the final pricing of specimens.   It is significantly easier to just cob gem rough off of specimens as the natrolite is dissolved than it is to painstakingly clean and prepare specimens.  The collecting world is fortunate that the supply of future specimens will be handled with the utmost care.

Specimen Preparation

So, what does it take to get a cleaned specimen of benitoite and/or neptunite?  Attractive specimens of this beautiful mineral assemblage just don't happen - they are literally crafted!  The process involves several steps which are all time consuming and require a bit of artistic aptitude.   Initially, uncleaned specimens are deposited in a container filled with hydrochloric acid of varying strength to perform an initial removal of natrolite through slow dissolving.  The natrolite is converted to a soluble gel which can be removed by running water and light brushing.  As crystals emerge from the natrolite it is necessary to wax portions of the specimen to prevent an undesired loss of natrolite.  The natrolite provides a pleasing contrast to both the benitoite and neptunite crystals (Too much etching leaves some crystals precariously perched by a thread or totally ruins the aesthetics of the specimen).   Once the desired amount of wax is applied the specimens are returned to the acid bath and etching continues.   Once the desired level of etching is reached the wax must be removed which is done chemically or by a heated water bath.  Next, the acid needs to be neutralized and residual silica gel removed by immersion in a strong basic solution (Red Devil pipe cleaner works great for this!).  The final cleaning is done with a toothpick or dental tool and a quick bath in an ultrasonic.  To be done right an average specimen requires no less than 8 hours of attention.  Many require a great deal more!  I have personally spent over 24 hours just on one rock in the past!  It is easy to see why specimen prices are what they are for this rare mineral!

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