Stone Professionals

Marble Soundness Classification

The assessment of physical properties in natural stone products is a challenging task. The challenge is not unique to the stone industry in that producers of all natural materials are charged with developing a system of classifying and categorizing those materials within their industry. The Marble Soundness Classification System has been with us, essentially unmodified, for more than half of a century (originating with the National Association of Marble Producers who merged with the Marble Institute in 1963). Its long, established use is definitely a result of its simplicity and effectiveness, but perhaps the greatest strength of this system is that it is linked only to material working properties, and specifically excludes any relationship with the market value of the materials. The intentional disassociation with market value has encouraged the objective review of natural stone materials for technical purposes, while avoiding the temptation to publish inappropriate classifications in the interest of inflating the cost of these materials. The recent incorporation of the Marble Classification data by ASTM into the C503 Standard Specification prompted the publication of this technical bulletin to educate Natural Stone Institute members about this system. Since this system has been so successful with marble and marble-like stones, the Natural Stone Institute is currently working on a similar classification system for granite and granite-like products.

This bulletin contains five sections:

  1. Marble Soundness Classification definitions and descriptions (revised since the publication of the Dimension Stone Design Manual, VI)-pages 1-2.
  2. How Marbles receive their Soundness Classification-pages 2-3.
  3. What is on the horizon for a Granite Soundness Classification System-page 3.
  4. Listing of Marbles with Soundness Classification designations-pages 3-10.

Full bulletin


Stones of North America

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