by L. L. Babcock
The following document is comprised of definitions and descriptions of *novaculite* from the geological literature. Novaculite is not a mineral; it is a massive white quartz rock used to make whetstones for sharpening knives, razors, and other steel implements. The highest quality novaculite known, termed 'Arkansas stone' comes from the Ouachita (pron. Wa-cha-taw) Mountains of Arkansas, USA. Arkansas Stone is off-white, massive, and featureless with no discernable bedding laminations. It is usually seen in the form of narrow tablets with a smooth sawn surface for sharpening.
The origin of novaculite is controversial and somewhat enigmatic. Here is the writer's version of the origin of novaculite, based upon the most recent geological thinking (cf Levin, 1992, pp. 361-362), the following descriptions, and the writer's direct observations. Originally, the rock later to become novaculite was deposited as an ultra-pure siliceous sediment known as bedded chert. These virtually pure silica cherts were primarily comprised of fibrous chalcedony, lesser amounts of microcrystalline quartz and amorphous silica (opal), and very few impurities. During subsequent depth of burial and low grade regional metamorphism, these high-purity silica beds were recrystallied under heat and pressure into microcrystalline quartz. In other words, novaculite is a metamorphic rock derived from a sedimentary rock known as bedded chert.
Three views of novaculite from the geological literature are presented below: 1) a general definition and description from the "Glossary of Geology" (Gary and others, 1972, p.485), 2) a mineralogical description of the strange microstructure of novaculite and derivation of the name by Frondel (1962, pp. 222,223), and 3) comments on the its origin by Krumbein and Sloss (1963, p. 184). A formal list of References Cited is given after the quotes.
a) A very dense and hard, even-textured, light-colored cryptocrystalline, siliceous sedimentary rock, similar to chert, but characterized by microcrystalline quartz over chalcedony and by accessory minerals such as feldspar and garnet. It was formerly supposed to be consolidated siliceous slime, but is now considered to be a result of primary deposition of silica under geosynclinal conditions. Novaculite is used as a *whetstone* for sharpening cutting instruments. The term is little used outside of Arkansas and Oklahoma where it is found in Lower Paleozoic strata. See also: Arkansas stone; Washita stone. Syn. razor stone; Turkey stone, galactite (obs).
b) A term used in southern Illinois for an extensive *bedded chert* (J. E. Lamar, in Tarr, 1938. p. 19).
c) A general term formerly used in England for certain argillaceous (clayey) stones that served as whetstones. (Gary and others, 1972, p. 485)
Arkansas stone A superior variety of *novaculite* found in the Ouchita Mountains of western Arkansas. Also a whetstone made of Arkansas stone. (p.38)
Turkey stone a) A very fine-grained siliceous rock (containing up to 25% calcite) quarried in central Turkey and used as a whetstone; *novaculite*. Syn. Turkey slate. b) turquoise. (p. 760)
Washita stone A porous, uniformly textured *novaculite* found in the Ouachita (Washita) River region and used esp. for sharpening woodworking tools. (p.784)
Novaculite. Novaculite is a white rock of uniform grain size and without lamination that is wholly composed of microgranular quartz. Under the optical microscope or electron microscope novaculite shows a randomly oriented aggregate of sharply defined polyhedral blocks or grains of quartz with smooth, slightly curved surfaces, somewhat resembling the air cells in foam. The rock may be a product of the low-grade metamorphism of chert beds. The well-known novaculite of Arkansas is of Devonian-Mississippian age. (Frondel, 1962, p.222)
The name novaculite is derived from the Latin *novacula*, *razor, or *sharp knife*, and alludes to the use of this material for whetstones and razor hones. (p.223)
Novaculite and similar bedded cherts, as illustrated by the Woodford (Devonian) of western Arkansas, are considered to be the result of primary deposition of silica under geosynclinal conditions. Some differences of opinion exist regarding depth of water, source of silica, and other factors, but the common occurrence of strongly siliceous sediments in geosynclinal tracts suggests a primary genetic relationship. (Krumbein and Sloss, 1963, p.184)
Frondel, C., 1962, "The System of Mineralogy of J. D. and E. S. Dana, v. 3, Silica Minerals": 7th ed., John Wiley and Sons, New York, 334p.
Gary, M., McAfee, R. Jr., and Wolf, C. L., eds., 1972, "Glossary of Geology": American Geological Institute, Washington, D. C., 805p.
Krumbein, W. C. and Sloss, L. L., 1963, "Stratigraphy and Sedimentation": 2nd ed., W. H. Freeman and Company, San Francisco, 660p.
Levin, H. L., 1992, "The Earth Through Time": 4th ed., Saunders College Publishing, HBJ, Fort Worth, 651p.
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