Novaculite, also calledArkansas Stone, is amicrocrystalline tocryptocrystalline rock type that consists ofsilica in the form ofchert orflint. It is commonly white to grey or black in color, with aspecific gravity that ranges from 2.2 to 2.5. It is used in the production ofsharpening stones. It occurs in parts ofArkansas,Oklahoma, andTexas, as well as inJapan and parts of theMiddle East. The namenovaculite is derived from theLatin wordnovacula, meaning a sharp knife, dagger, or razor,[2] in reference to its use in sharpening. The first recorded use of the termwhetstone was in reference to a honing stone from Arkansas.[3]
The novaculite beds of the south-central United States were deposited in theOuachita Geosyncline, a deep-water marine trough, duringSilurian to earlyMississippian time. Sedimentation consisted primarily ofsiliceous skeletal particles of marine organisms such assponge spicules andradiolaria, and very fine-grained, wind-blownquartz particles; there was very littleargillaceous sedimentation during novaculite deposition.[5] The novaculite beds were later subjected to folding and uplift, and probably low-grademetamorphism, during theOuachita orogeny in earlyPennsylvanian time.[1]
Because novaculite is very hard and dense, it has been mined since prehistoric times, first for use as arrow and spear points, and later to make sharpening stones. Novaculite-rich sharpening stones from Arkansas are calledArkansas stones;[6] stones produced in theOttoman Empire (Syria, Lebanon, and Israel) were calledTurkey stones;[4] and novaculite stones were also produced in Japan.[4] The crystal grains of novaculite measure 3 to 5 microns, equivalent to a US grit size of 600-1200, making novaculite suitable for the final stages of metal blade sharpening. Novaculite sharpening stones are classified by density.[7]
The weathered upper strata of Arkansas novaculite, known astripoli or "rotten stone", are rich in silica and have found a niche market as a performance additive or filler in the coatings, adhesives, sealants, andelastomer industries. Tripoli is mined just east ofHot Springs, Arkansas by the Malvern Minerals Company.[3]
Folk, R.L., and E.F. McBride, 1976,The Caballos Novaculite revisited Part I: "origin of novaculite members. Journal of Sedimentary Petrology. 46659-669
Folk, R.L., and E.F. McBride, 1978,Origin of the Caballos Novaculite. in S.J. Mazzullo, ed., Tectonics and Paleozoic facies of the Marathon Geosyncline, West Texas: Permian Basin Section, Society for Sedimentary Geology, SEPM, Publication no. 78-17:101-130.
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.
Krumbein, W.C. and Sloss, L.L., 1963,Stratigraphy and Sedimentation: 2nd ed., W. H. Freeman and Company, San Francisco, 660p.
Lowe, D.R., 1975,Regional Controls on Silica Sedimentation in the Ouachita System.Geological Society of America Bulletin. 86:1123-1127
Lowe, D.R., 1976,Nonglacial varves in lower member of Arkansas Novaculite (Devonian), Arkansas and Oklahoma.American Association of Petroleum Geologists Bulletin. 60:2103-2116.
Lowe, D.R., 1977,The Arkansas novaculite: some aspects of its physical sedimentation. in C.G. Stone, and others, eds., Symposium on the geology of the Ouachita Mountains. Arkansas Geological Commission Miscellaneous Publication 13:132-138.
Lowe, D.R., 1989,Stratigraphy, sedimentology, and depositional setting of pre-orogenic rocks of the Ouachita Mountains, Arkansas and Oklahoma, in R.D. Hatcher, Jr., W.A. Thomas, and G.W. Viele, eds., The Appalachian-Ouachita orogen in the United States. The Geology of North America. F-2:575-590, Geological Society of America, Boulder.
McBride, E.F., 1989,Stratigraphy and sedimentary history of Pre-Permian Paleozoic rocks of the Marathon uplift, in R.D. Hatcher, Jr., W.A. Thomas, and G.W. Viele, eds., The Appalachian-Ouachita orogen in the United States. The Geology of North America. F-2:603-620, Geological Society of America, Boulder.
