LIMESTONE QUARRY

The white scar that is visible on the northern portion of the Santa Rita Mountains near the old ghost town of Helvetia is an outcropping of calcium carbonate, or limestone.  It is the site of an active open pit mine operated by Imerys Marble Inc., which, in October 2003 employed 12 people.  The company owns 43 mining claims of about 20 acres per claim.  The mine operates 24 hours per day, seven days per week and produces about 100,000 tons of material per year. About twenty truckloads of material depart the mine site each day.  It is estimated that the mine could produce at that rate for the next 50 years. 

The white scar that you see is not a result of quarry operations.  The whole mountain in that area is essentially limestone with very little overburden and the erosion that has taken place over the years has given the impression that scar enlargement is the result of quarry operations.  This is not the case.  The quarry that is currently being worked is not visible from the Green valley area but is hidden behind an intervening hill. 

Even though the name of the company that operates the mine is the Imerys Marble Company, no marble is produced at the mine. Marble is metamorphosed limestone and none of the limestone deposits at the mine had been exposed to the temperatures and pressures necessary to convert them to marble. 

Some of the uses for the calcium carbonate products produced at the mine are:

-  3/16” Decorative Aquarium Rock.
-  5/8” Decorative Landscape Rock.
-  7/8” Decorative Landscape Rock.
-  Calcium supplement used in animal feed.
-  Filler in paint and roof coatings.
-  Filler in drywall and in drywall plaster and grout.
-  Pool mix, which is mixed with white cement for the finishing coat of plaster for
    swimming pools.
-  Plus 5 Athletic Field Marker used for making the white stripes on athletic fields.
-  GM80 which is used as a fire retardant.

The calcium carbonate produced at the mine has not been approved for human consumption by the Food and Drug Administration so it can not be used in calcium supplements such as Tums or Rolaids.  Imerys Marble does have a mine in Alabama, which has been certified for use in these products.

Summary prepared by T. Johnson from articles in the19 January 2001 Arizona Daily Star, the 30 April 2003 Green Valley News and Sun and 1 October 2003 discussions with the Imerys Plant Manager.

Additional Material: GVHC Library File 34