Today’s Ask-a-Geologist Question: Marble vs. Quartzite

QuartziteMarbleQuestion:  How could mineral hardness be used to tell quartzite (shown right) from marble (shown left)?


Answer:
  I don’t think that hardness would be the best test.   In theory, quartzite should be harder because it is made of Quartz which has a hardness of 7 on the Mohs scale and Marble is made of calcite which is has a hardness of 3 on Mohs scale.  The best test is the “fizz test.”  If you drop a dilute acid on the rocks, the marble will bubble or fizz.  You can use vinegar or lemon juice since they are very weak acids and see if you can observe the fizz.  Anything made of calcite should fizz but quartz will not.

One Response to “Today’s Ask-a-Geologist Question: Marble vs. Quartzite”

  1. Why would a sculptor choose marble over quartzite for creating a statue?

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