Searles Lake Gem and Mineral Society
See  Flyer  for dates and times
Blow Hole Field Trip
The Blast               The Blow Hole Minerals

The crystals found during this field trip, especially the rare hanksite which is found at only one other place in the world, occur within the
Upper Salt at a depth of 25 to 40 feet beneath the salt surface.  This depth, plus the fact that the lake brine level is almost at the surface,
means that without help from Searles Valley Minerals it would be impossible for our Gem-O-Rama visitors to find anything.

The preparations for this field trip begin about two weeks before the show.  Searles Valley Minerals technicians begin by choosing a site
where good crystals are thought to be available and where there is a large enough flat area to allow field trip parking.  Then locations for
about 15 holes are marked, each about 100 feet from it's neighbors. A rotary drill bores 16 inch diameter holes into the salt body
at each location.  These holes, which are typically 40 feet deep,  provides the access needed to recover the hanksite and other crystals.
The second step occurs four days before the field trip when an licensed explosives technician from Alpha Explosives arrive on site to blast the holes.
The blast objective is to loosen crystals within the target depth so they can then later be "blown" onto the surface.  After examining the site and talking
with the SVM geologists and technicians, the explosives expert assisted by an SVM crew prepares for setting up the blast.

The explosives technician, assisted by a crew of SVM technicians,  measures and marks the primer cord so that the explosives can be accurately
set at the depths where the crystals are to be loosened.

Blocks of exposive are then taped together along the primer cord to provide the explosive force.  To avoid damage to the surface, the depth is set so
that all the explosives are below the 20-foot depth.  
Technicians tape explosives to primer cord

Weights are hung on the bottom end of the primer cord to make sure the explosive assembly goes all the way to the bottom of the
 hole. A weight and primer cord/explosive assembly is then carefully lowered into each hole.  Sandbags are also placed on the primer
cord at the top of the hole to keep it in place.
Explosives into the hole

Go to The Blast.
Go to The Blow Hole Minerals
Go to  Gem-O-Rama Site Map

Searles Lake Gem and Mineral Society
P. O. Box 966
Trona, CA 93592-0966
Phone (760) 372-5356
FAX (760) 372-4799

Home  |  Site Map  | Revised 09/22/2013

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