Martin Marietta Magnesia Specialties Announces Price Increases

BALTIMORE, Maryland - May 4, 2006 - Martin Marietta Magnesia Specialties, LLC is initiating price increases for its hard burned, rotary produced Industrial and Agricultural lines of magnesium oxide. The list price for all MagChem(R) 10 grades, all AniMag(R) grades, all CropMag(R) grades and all ProMag(R) grades will increase a minimum of 5%, with increases in off list pricing higher. These price increases will become effective June 1, 2006, or as contracts allow.

Magnesia Specialties manufactures an extensive range of magnesia-based products used in industrial, environmental, water treatment, flame retardant, plastic and rubber, specialty and agricultural applications.

Martin Marietta Magnesia Specialties, LLC, a subsidiary of Raleigh North Carolina based, Martin Marietta Materials, Inc. (NYSE:MLM), is a leading global producer of magnesium oxide and magnesium hydroxide products.

For more information on Martin Marietta Magnesia Specialties' products and services, visit www.magspecialties.com.