Marl

Description

A friable mixture of Clay that contains a high proportion of Calcium carbonate. Marls are secondary clays that often contain Sand, iron oxide, and other impurities. Marls are most often used as alkaline additives to soil. As a pottery clay, marl tends to be aplastic and is often used for slipware, Earthenware, and Brick. Some examples of marls used in pottery are (Fournier 1996):

- Keuper marl: contains Magnesium carbonate and Gypsum; variable in color

- Etruria marl: contains almost no Lime

- Cambridge marl: contains about 40% lime

Diatomaceous marl

Synonyms and Related Terms

Keuper marl; Etruria marl; Cambridge marl; calcareous clay; marga (Port.)

Additional Information

R. Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Co., Radnor, PA, 1996.

Sources Checked for Data in Record

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 118

• Henry Hodges, Artifacts: An Introduction to Early Materials and Technology, Ronald P. Frye, Kingston, Canada, 1988

• Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000