THE GOLD OF THAT LAND: Biblical Minerals & Rocks  


 

20.     clay

Hebrew:

    1. ma'beh, clay ground. 1 Kings 7:46, 2 Chronicles 4:17.

    2. chmer, a slurry of clay. Job 9:30, 10:9, 13:12, 27:16, 33:6, 38:14; Isaiah 29:16, 45:9, 64:8; Jeremiah 18:4, 6.

    3. tyt, a sticky mire or mud. Psalm 40:2, Isaiah 41:25, Nahum 3:14.

    4. melet, smooth kneaded clay. Jeremiah 43:9.

    5. chasaph, a clod of earth. Daniel 2:33-45.

    6. abtyt, "thick clay." Habakkuk 2:6.

Greek: pelos. John 9:6-15, Romans 9:21.

Probable Identification:

    Only ma'beh, melet, and pelos mean clay in the strict sense of the word. The other Hebrew words are more colloquial terms corresponding to dirt, mud, mire, or muck. "Thick clay" in Habbakuk 2:6 is more correctly rendered as pledged or pawned goods.

Mineralogy:

    Clay in modern usage denotes fine-grained sedimentary particles of less than 0.005 mm diameter on the Wentworth grain size scale. Ordinary clay is a plastic mixture of clay minerals, colloidal silica, calcium carbonate, aluminum and iron oxides, with various other impurities.

    Clay minerals are hydrous aluminosilicates that take the form of very minute flaky grains. The principal clay mineral species, kaolinite, illite, montmorillonite, mixed-layer clays, and attapulgites, are the products of chemical weathering of feldspars and ferromagnesian minerals in igneous rocks. Kaolin or china clay is white and chemically inert. Other clay minerals are chemically reactive to varying degrees.

    Bender reports the occurrence of kaolinitic clays in Jordan. A 4.2 m (14 ft) layer is exposed at Mahis, 17 km west-northwest of Amman, and a 2.8 m (9 ft) bed of red, yellow, and blue-grey clay is exposed near Ghor Khabid, on the east side of the Jordan valley, about 25 km (15 miles) north of the north tip of the Dead Sea. Both deposits occur in greyish white shaley zones in the upper part of the Lower Cretaceous Kurnub Sandstone.

Historical Background:

    Residents of horticultural communities at Jericho and elsewhere in the Fertile Crescent shaped clay into figurines and unfired bricks during the 10th millennium BC. The use of clays in ceramic and structural clay products began long before the use of metals, and fired pottery dates from at least the 6th millennium BC. Women may have coated the insides of wicker baskets with clay in order to carry seeds or water. The discovery of fired pottery may have begun with the practice of wrapping meat in leaves and an envelope of clay before baking it in an open fire place. The earliest vessels were made by winding coils of clay into spirals and molding them by hand. The invention of the pottery wheel and glazes somewhere in the Middle East by 4000 BC ranks as one of the key inventions behind the rise of civilization.

The pottery wheel made possible the mass production of standardized vessels for storing and carrying water, wine, olive oil, and grains. In turn, standardized pottery brought about such a surge in the volume of trade, especially in wine and olive oil, that traders had to develop new methods of keeping business accounts. Trial-and-error in making pottery glazes also led in time to the development of faience and glass.

    In Mesopotamia, clay tablets provided the earliest medium for keeping business records and subsequently for writing. Denise Schmandt-Besserat (2002) traces the descent of Mesopotamian cunieform writing on clay tablets from clay tokens or counters in the form of cones, spheres, disks, cylinders, and ovoids. Job 38:14 records the use of an official seal upon a clay document, a widespread ancient practice. Potsherds served for informal notes.

    The mineralogy and plasticity of a clay determine its best use. The purest grades of kaolin are used today in the manufacture of porcelain and fine china. Modern industry also uses great quantities of unfired clay in paper coatings, absorbents, fillers, cement, oilfield drilling muds, and numerous other applications.

    Pharonic potters worked with either Nile mud or a marly clay from between layers of limestone. Nile mud turns red-brown when fired, but pottery made from the marly clay varied from white to yellowish to green. After kneading their clay, potters added fine quartz or lime sand to keep it from cracking while drying and to improve its strength after firing. Baked and pulverized clay might take the place of sand.

While the earliest pottery was fired in open fires, excavations at Jericho confirm that potters soon learned to use kilns that required less fuel to maintain the necessary temperatures of 700 to 900oC. Firing at this low temperature range converts clay into the soft, porous ceramic termed earthenware.

Strictly-observant Jews in New Testament times considered earthenware pottery subject to defilement, and they destroyed it after us or else they bought more expensive stone vessels. Earthenware of Greek and Roman origin nevertheless had attained high standards of artistry in form, finish, and decoration. Terra sigillata ware, for example, was a bright red, polished earthenware of high quality that became  popular throughout the Roman Empire at this time. Terra sigillata ware was mass-produced by casting in molds and decorated by stamping.

Firing at temperatures above 1000oC produces a harder, denser ceramic called stoneware, and firing at 1400 to 1700oC produces white porcelain, the noblest ceramic, from a mixture of 50% kaolin, 25% quartz, and 25% feldspar. Stoneware was available in Roman times, but the Chinese discovered the secrets of making porcelain well after biblical times, during the Tang Dynasty (618-907 AD).

The manufacture of porcelain tableware today begins with molding blank pieces from a clay cake or liquid clay slip prepared according to a proprietary recipe. Molded pieces go into a kiln for firing at up to 9550C. This first stage of firing yields a fragile, porous material termed biscuit or bisque. Pieces of bisque are then dipped in a glaze, which is a proprietary liquid mixture of powdered quartz, feldspar, dolomite, and chalk. Dipped pieces return to the kiln for their second stage of firing at 1400 to 1700oC. Firing at these temperatures melts the glaze and vitrifies the bisque, yielding durable, translucent pieces with a shiny finish.

In addition to vessels, ancient potters made household items such as figurines, spindles for spinning, and weights for looms. Metalworkers soon learned the use of clay molds and the lost-wax technique for casting jewelry, weapons, and vessels in bronze and other metals.

    Celadonite and glauconite, which are greenish, iron-rich clay minerals, provided green pigments for painting.

Biblical Background:

    Solomon commissioned the casting of bronze vessels in clay ground in "the plain of Jordan between Succoth and Zarethan" (1 Kings 7:46). Cunningham Giekie placed the location in the Jordan Valley near Qarn Sartabah and he commented that the soil is especially suitable for foundry molds. Lisan marls and other Pleistocene alluvial clays occur in this area.

    Clay became the biblical, if not universal, metaphor for humanity (Isaiah 64:8), the human body (Job 4:19), and moral frailty (Daniel 2:31-45). The potter treading his clay in Isaiah 41:25 portrays the Lord's sovereign control over human rulers and events, whether they know it or not. The apostle Paul alludes to Isaiah (Romans 9:21) and transforms the Hebrew imagery into Greek by comparing the light of the glory of God shining in our hearts to a treasure in jars of clay (ostrakinos skeous, 2 Corinthians 4:7). The bill of materials for the Holy City in Revelation 21 omits any mention of bricks, in pointed contrast to the aborted tower of Babel and the offensive brick altars of Isaiah 65:3. The use of bricks in the tower of Babel stands for the assertion of human pride and independence of the Rock of Ages, and for the inevitable brevity and failure of efforts that deny God.

    Fuller's earth is a non-swelling calcium montmorillonite clay formed by the alteration of volcanic ash laid down in a marine environment. It is an absorbent and is used in "fulling" or thickening woolen fabric after weaving, as well as for cleaning soiled garments. The Bible alludes to the fuller's trade (2 Kings 18:17: Isaiah 7:3, 36:2; Malachi 3:2; Mark 9:3), but not specifically to fuller's earth.

 

Sources:

Bender, op. cit.; 72, 168.

Canby, Jeanny Vorys, 1995. Jewelry and personal arts in Anatolia. In Sasson, op. cit.; 1673-1682.

Giekie, Cunningham, 1897. Holy Land and the Bible. London: Cassell & Co.

Hurlbut, 1952, op. cit.; 348.

_____, 1970, op. cit.; 34-35.

Logan, William Bryant, 1995. Dirt: The Ecstatic Skin of Earth. New York: Riverhead Books.

Lucas & Harris, op. cit.; 49-50.

Romano, op. cit.; 1613-1615.

Schmandt-Besserat, Denise, 2002. Signs of Life. In Meinhardt, Jack, ed., The Origins of Things. Washington, DC; 21-27.

Wengrow, David, 1998. "The changing face of clay": continuity and change in the transition from village to urban life in the Near East. Antiquity; 72:783-95.


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