Mica and diamonds at the Crater

By Waymon Cox

  Greetings from Crater of Diamonds State Park!  One of the easiest methods of Visitors have been known to walk, sit, or even crawl among the plowed rows of the search area while looking for diamonds!

  diamond search area, but many of the most thorough visitors painstakingly collect another shiny mineral that has the appearance of diamond dust!

  Phlogopite, or magnesium mica, is a flat, shiny found at the Crater.  It is a soft, lightweight, and easily breaks into flat, six-sided sheets.  Its copper-colored surface displays an eye-catching metallic shine in the sunlit in one direction, like a mirror.  Crater diamonds, on the other hand, have smooth, rounded facets that reflect light at many angles.  While mica reflects sunlight one way, a Crater diamond will shine at many angles.  The glittering appearance of mica may be exciting at first, but with a little practice one can learn to ignore the brief flashes of mica and look for the lasting shine of a diamond.

  While specimens from the Crater make nice souvenirs, larger quantities of phlogopite mica are mined elsewhere for many uses.  An excellent insulator, phlogopite is used in vehicle brakes and clutch plates to prevent overheating and reduce noise and vibration.  Because it remains stable up to 1600 degrees Fahrenheit, phlogopite mica is also used to insulate power cables for heaters, blast furnaces, boilers, kilns, and other high-temperature applications.  It is used in our homes as a surfacing agent in wallboard joint cement and in our workplaces as an insulator for brick buildings like the park’s Diamond Discovery Center!

  We hear it all the time while identifying rocks and minerals:  “I don’t think these are worth anything.  I thought they were pretty, so I picked them up!” While we often base a mineral’s appeal on its physical beauty or potential monetary value, every rock and mineral is used for something—its true value depends on what you do with it!
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Search area last plowed:  December 4, 2012

Most recent significant precipitation:  January 12, 2013

Diamond finds for the week of January 13, 2013 (100 points = one carat):

No diamonds registered January 13 – 15.

January 16 – Adam Hardin, Barberton, OH, 2 pt. yellow, 7 pt. brown, 16 pt. yellow

January 18 – Kenny & Melissa Oliver, Rosston, AR, 2 pt. brown, 2 pt. white, 3 pt. white, 3 pt. brown, 3 pt. yellow, 4 pt. brown, 4 pt. white, 6 pt. yellow, 8 pt. white, 10 pt. brown, 15 pt. white, 16 pt. white, 21 pt. white

January 19 – Mary Jane Carroll, Stonewall, LA, 11 pt. yellow

Crater of Diamonds Home Page
209 State Park Road
Murfreesboro, AR 71958
Email: craterofdiamonds@arkansas.com
Phone: (870) 285-3113

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