THE GOLD OF THAT LAND: Biblical Minerals & Rocks  


 

24.     crystal

Hebrew:

    1. zekūwīth, pure and clear stuff. Job 28:17.

    2. qōrach, ice. Ezekiel 1:22

    3. 'elgābīsh, stones as hard as crystal. Ezekiel 13:11, 13; 38:22.

Greek: crustallos, ice crystal; crustallizo, ice,  crystalline. Revelation 4:6, 21:11, 22:1.

Probable Identification: biblical crystal is clear, colorless, crystalline quartz or "rock crystal."

Mineralogy:

    Quartz forms long prismatic hexagonal crystals that terminate in rhombohedral faces in many combinations, commonly with horizontal striations. Quartz crystals commonly occur in intergrown, twinned masses that may reach great size. A rock crystal ball in the collection of the Smithsonian Museum weighs 106 pounds (48.5 kg) and was cut from a thousand-pound block. Quartz has a hardness of 7 and a specific gravity of 2.65.

    As the most abundant mineral of the earth's crust, quartz numbers more ornamental and semiprecious varieties than any other mineral. O'Donoghue lists 146 distinctively colored, gem varieties of crystalline quartz that have long had their own names, such as amethyst, bull quartz, cairngorm, cat's-eye, citrine, rose quartz, tiger eye, and smoky quartz.

Realization that they are varieties of quartz began to dawn only in the early eighteenth century with Nicholas Steno’s 1669 discovery that quartz crystals have constant interfacial angles regardless of their differences in color, size, shape, or locality.

A trace of iron gives amethyst and citrine their hues. Although the tint of rose quartz is commonly ascribed to a trace of titanium or magnesium, mineralogist William H. Dennen determined that the trace content of titanium is very low and that it occurs in the form of microscopic rutile needles. Their systematic orientation within clear quartz produces a scattering of light rather than pigmentation. Exposure to radioactive minerals accounts for smoky quartz. Rutilated quartz contains fine needles of rutile, and aventurine has lustrous inclusions of glistening mica or hematite scales which are oriented in a shimmering "Schiller" structure. Green aventurine from India contains flakes of a bright green, lithium-rich mica. Star quartz crystals have inclusions of rutile perpendicular to their long axis, and a well cut crystal displays them as starry rays of light. Tiger eye is crystalline quartz which has replaced blue asbestos (crocidolite) while preserving its fibrous structure. The sole source of yellow and blue tiger eye is metamorphic rock of the Precambrian Griquatown Series in the Asbestos Mountains near Prieska, South Africa.

    Crystalline quartz occurs as shapeless grains in light colored igneous rocks, and massive crystals occur in granite pegmatites. Rock crystal occurs worldwide in vein quartz and in geodes in limestones. Hydrothermal solutions precipitate vein quartz in igneous and metamorphic rocks at lower temperatures than those at which igneous rocks crystallize. Quartz precipitates from solution in geodes and void spaces of all sizes in sedimentary rocks of all kinds. Modern producers of rock crystal include Arkansas, Brazil, Germany, and Madagascar.

Historical Background:

    People in ancient times believed that clear rock crystal was petrified water ice. The Greek name crustallos reflects that belief.

    The ancient Egyptians used rock crystal from near Aswan and every other color of quartz from predynastic times onward to make beads, inlaid eyes, vases, knobs, and other ornamental objects. One of the treasures of Troy is a lion's head of rock crystal. The Babylonians sent cylinder seals of rock crystal as gifts to other rulers, and a Neo-Assyrian text says, "A seal of crystal (portends) that he shall walk in joy of heart."

John Layard's discovery of a rock crystal magnifier at Nimrud in 1850 shows that the Assyrians knew how to grind lenses as early as the second millennium BC. The Greeks and Romans also made lenses from rock crystal.

    Quartz crystals have the property of piezoelectricity or developing a surface electric charge when compressed. Thin slices of high quality quartz are used as resonators to generate waves of a fixed frequency in electronic applications that range from computers to solar electric cells. Synthetic quartz crystals supply most of this demand.

 

Sources:

Dennen, William H., & Anita M. Puckett, 1971. On the chemistry and color of Rose Quartz. Mineralogical Record: 2-5, 226-227.

Hurlbut, 1952, op. cit.; 319-321.

Lucas & Harris, op. cit.; 402-403.

O'Donoghue, 1987. op. cit.; 102-105.

Pittman, op. cit.; 1589-1603.

Ralph, Jolyon, 1993-2004. http://www.mindat.org/min-3337.html 

Schumann, op. cit.; 116-153.

 

 


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