« Polar Jade Lotus Peak | Main | Jade Tectonics in Central America »
Saturday
Aug072004

Jade: Occurrence And Metasomatic Origin

1 HARLOW, G. E. and 2 SORENSEN, S. S.

1 American Museum of Natural History, New York, NY, U.S.A.;
2 Smithsonian Institution, Washington, DC, U.S.A.

The term jade, as used in geology and gemology, refers to two extremely tough, essentially monomineralic rocks used for carvings and gems. Amphibole jade is nephrite, a tremolite-actinolite [Ca2(Mg,Fe)5Si8O22(OH)2] rock with a felted, microcrystalline habit, and pyroxene jade is jadeite [NaAlSi2O6] rock (jadeitite) which varies from micro- to macrocrystalline textures. Both rock types have received relatively little attention due to their scarcity, minor economic importance, and cryptic petrography. The geological interpretation of both jade types has been hindered by poor exposure and the occurrence of major jadeitite deposits in politically unstable countries. However, recent investigations show not only that the jades share some common geological characteristics, but both result from and record important Earth processes. Nephrite is the more common and less valuable of the two jade types. Important deposits occur at the Polar, Kutcho, and Ogden Mtn. properties in northern British Columbia, Canada (Gabrielse, 1990); along the Yurungkash and Karakash (White Jade and Black Jade) Rivers, Kunlun Mtns., Xinjiang, China (see Webster, 1975); SW of Lake Baikal in the East Sayan Mtns., Siberia, Russia (Prokhor, 1991); the Barguzin-Vitim Massif, Central Vitim Highland (East of Lake Baikal), Siberia, Russia (Sekerin et al., 1997); near Cowell, South Australia (Flint and Dubowski, 1990); the Westland (Arahura River– Cooper, 1995), the Livingstone, Nelson, Otago, and South Westland fields on South Island, New Zealand (Beck, 1984 & 1991); northeastern Taiwan (Wand,. 1987); Jordansmuhl, Poland (Visser, 1946); in the Granite Mtns., Lander Co., Wyoming (Madson, 1978); and along the Noatak & Kobuk Rivers south of the Brooks Range in Alaska (Loney and Himmelberg, 1985). Many minor occurrences are associated with small ultramafics in ophiolite belts around the world, such as in the Western and Central Alps, central Brazil, and the ophiolite belts from California to Alaska. Nephrite ranges from pure, white tremolite (“mutton-fat jade”) to dark green actinolite and occasionally black from Fe-actinolite or oxide / graphite pigment. Rarely nephrite can have an emerald-green color from Cr 3+ in sodic-tremolite/actinolite. Staining to ochre colors from iron oxidation in weathering rinds of boulders is common. Minor coexisting minerals include diopside, calcic garnet, magnetite, chromite, graphite, apatite, rutile, pyrite, datolite, vesuvianite, prehnite, talc, serpentine polymorphs and titanite. Nephrite bodies result from contact and/or infiltration metasomatism of either dolomite by magmatic fluids or silicic rocks by serpentinite fluids. White nephrite is derived from siliceous metasomatism of dolomite by a “granitic” body or its pneumatolytic / hydrothermal apophyses (e.g., Yurung-kash [White Jade River], Kunlun Mtns.). However, dolomite metasomatism can yield green to black jade if a source of iron is present, such as from mafic bodies, iron-stone (e.g., Cowell and presumably Karakash, too). Other nephrites involve either metasomatism of silicic rocks in serpentinite (or serpentinite melange) by Ca-Mg-rich fluids or a boundary reaction/infiltration metasomatism of silicic rocks or fluids from them acting upon antigorite serpentinite and serpentinite fluids (see Karpov et al. 1988; Suturin, 1986), both being post-igneous processes (the serpentinite affinity places such nephrite deposits among the global distribution of ophiolite complexes, the scars of ocean basins closed by plate tectonics – Fig. 1). Ca saturation is most likely produced by clinopyroxene breakdown during maximum serpentinization, however, in part, it may also be the result of decreasing P and increasing T upon fluids rising through (and with) serpentinite melange—see below. Conditions can range from the high T limit of greenschistamphibolite facies (< ph2o="Ptotal"> 5-6 kbar (bounding reaction is Jd+W=Anl) rather than > 8-11 kbar (bounding reaction Jd+Qtz=Ab) for the low T environments (200 to 400 °C based on assemblages). Nevertheless, this represents substantial depth (>16 - 20 km) for a fluid that deposits jadeite in serpentinite (serpentinizing peridotite) by rising through an accretionary wedge or back along subduction-related faults. Fluid inclusions and O/H isotopic systematics infer the predominance of a seawaterlike fluid entrained during subduction rather than the product of dehydration of deep metamorphic minerals, at least for Guatemala (Johnson and Harlow, 1999). Trace element studies of jadeite from jadeitites manifest considerable heterogeneity, suggesting diverse fluid trajectories for different jadeitites in the same deposit, although overall trends suggest some deposits may be derived primarily from sediments (perhaps in Guatemala) while others may record a significant felsic-igneous component (perhaps Myanmar) (Sorensen and Harlow, 1998, 1999, and in prep.). The high-pressure origin of jadeitites associates them in the belts of eclogites and blueschists around the world – Fig. 2. Jadeitite formation requires devolatilization, primarily dewatering of sediments, within a subducting slab at depths down to the blueschist-to-eclogite transition. Such fluids will be enriched in components that are nearly saturated with jadeite (e.g., Manning, 1998). These fluids may become channelized through overlying serpentinized peridotite (of unknown provenance) which can diapirically rise along a fore-arc transform/lateral fault, which may be related to final oblique convergence of continental (Myanmar) or island arc (Guatemala) terrane. Crystallization of jadeite provides a focus for brittle fracture, fluid flow, and further deposition of jadeite during serpentinite diapirism and faulting. Fluid travels down P but up T which is key to the sequence jadeitite followed by albitite found at all jadeitite occurrences. Fractionation by jadeite crystallization and decrease in P progressively enriches the diopside content in the rising fluid, so pyroxene crystallization trends to omphacite at crystal rims. Increased silica activity at shallower depths leads to the co-crystallization of albite + omphacite or diopside. Interaction of the fluid with tectonic blocks entrained in the host serpentinite can lead to jadeitization, or in the case of basaltic blocks, the formation of Fe-rich omphacitites or omphacite-rich amphibolites. At the top of the system tremolite may saturate—with possible formation of nephrite. The diapiric rise of serpentine, perhaps enhanced by the collision process, exposes fossil jadeitite, however the rapid uplift may also result in a short duration of exposure, explaining the paucity and young age of most jadeitite deposits. The formation of most nephrite and jadeitite deposits records events at convergent margins that involve fluid interactions in and around serpentinizing peridotite at depths from perhaps > 50 km to the near surface. Preservation of the jade is a relatively rare event that may require special tectonic conditions and a limited range of peridotite hosts for jadeitite and perhaps nephrite. Jades are thus unique probes of convergent margins and fluids derived from subduction zone devolatilization—profoundly interesting geologically as well as materially and archaeologically.

References:

Beck, R., 1984. New Zealand Jade. A.H. & A.W. Reed, Ltd., Wellington. 173p.
Beck, R., 1991. Jade in the South Pacific. In: Keverne, R. (Ed.) Jade. Van Nostrand Reinhold: 221-258, New
York.
Bender, F., 1983. Geology of Burma. Gebrüder Borntraeger, 293, Berlin.
Chhibber, H. L., 1934. The Mineral Resources of Burma. MacMillan and Co., 320, London.
Chihara, K., 1971. Mineralogy and paragenesis of jadeites from the Omi-Kotaki area, Central Japan.
Mineralogical Society of Japan, Special Paper 1: 147-156.
Coleman, R. G., 1961. Jadeite deposits of the Clear Creek area, New Idria district, San Benito County,
California. Journal of Petrology 2: 209-247.
Cooper, A. F., 1995. Nephrite and metagabbro in the Haast Schist at Muddy Creek, Northwest Otago, New
Zealand. New Zealand Journal of Geology and Geophysics 38: 325-332.
Dobretsov, N. L., 1963. Mineralogy, petrography and genesis of ultrabasic rocks, jadeitites, and albitites from
the Borus Mountain Range (the West Sayan). Academia Scientifica USSR (Siberian Branch), Proceedings of
the Institute of Geology and Geophysics 15: 242-316.
Dobretsov, N. L. and Ponomareva, L. G., 1965. Comparative characteristics of jadeite and associated rocks
from Polar Ural and Near-Balkhash Region. Academia Scientifica USSR (Siberian Branch), Trudy, Institute of
Geology and Geophysics 31: 178-243.
Flint, D. J. and Dubowski, E. A., 1990. Cowell nephrite jade deposits. In: Hughes, F.E. (Ed.), Geology of the
mineral deposits of Australia and Papua New Guinea; Volume 2. Australasian Institute of Mining and
Metallurgy, 14: 1059-1062, Melbourne.
Gabrielse, H., 1990. Cry Lake jade belt, north-central British Columbia. Open-File Report 2262. Geological
Survey of Canada, Calgary.
Hargett, D., 1990. Jadeite of Guatemala: A contemporary view. Gems and Gemology, 26: 134-141.
Harlow, G. E., 1994. Jadeitites, albitites and related rocks from the Motagua Fault Zone, Guatemala. Journal of
Metamorphic Geology, 12: 49-68.
Hughes, R.W., Galibert, O., Bosshart, G., Ward, F., Oo, T., Smith, M. Sun, T.T., and Harlow, G.E., 2000.
Burmese Jade: The Inscrutable Gem. Gems and Gemology 36, No. 1: 2-26.
Johnson, C. A. and Harlow, G. E., 1999. Guatemala jadeitites and albitites were formed by deuterium-rich
serpentinizing fluids deep within a subduction-channel. Geology 27: 629-632.
Karpov, I. K., Chudnenko, K. V. and Suturin, A. N., 1988. Physicochemical modeling of processes of contactinfiltration
metasomatism. Transactions (Doklady) of the U.S.S.R. Academy of Sciences: Earth Science
Sections, 297: 189-192.
Komatsu, M., 1987. Hida “Gaien” Belt and Joetsu Belt. In: Pre-Cretaceous Terranes of Japan. (K. Ichikawa,
S. Mizutani, I. Hara, S. Hada, and A. Yagi, eds.) IGCP project No. 224: 25-40. Nippon Insatsu Shuppan Co.,
Ltd., Osaka 413pp.
Loney, R. A. and Himmelberg, G. R., 1985. Ophiolitic ultramafic rocks of the Jade Mountains-Cosmos Hills
area, southwestern Brooks Range. In: The United States Geological Survey in Alaska; accomplishments during
1984. U. S. Geological Survey Circular: 13-15. Reston, VA.
Madson, M. E., 1978. Nephrite occurrences in the Granite Mountains region of Wyoming. In: Boyd, R. G.,
Boberg, W. W. and Olson, G. M., (Eds.) Resources of the Wind River Basin. Guidebook - Wyoming
Geological Association. 30: 393-397, Casper, WY.
Manning, C. E., 1998. Fluid composition at the blueschist-eclogite transition in the model system Na2O-MgOAl2O3-
SiO2-H2O-HCl. Schweizerisches Mineralogisches und Petrographisches Mitteilungen 78/2: 225-242.
Morkovkina, V. F., 1960. Jadeitites in the hyperbasites of the Polar Urals. Izvestia Akademia Nauk SSSR
Izvestia, Seria Geologicheskaya, no. 4: 78-82.
O’Hanley, D. S., 1996. Serpentinites, recorders of tectonic and petrological history: Oxford Monographs on
Geology and Geophysics 34, 256, Oxford.
Prokhor, S. A., 1991. The genesis of nephrite and emplacement of the nephrite-bearing ultramafic complexes of
East Sayan. International Geology Review 33: 290-300.
Sekerin, A.P.; Sekerina, N.V., Men-shagin, Yu.V. and Lashchenov, V.A., 1997. Printsipy prognozirovaniya
neftenosnykh oblastey (Translated Title: Principles for prediction of nephrite deposits). Otechestvennaya
Geologiya. 1997, 5: 42-46.
Smith, D. C. and Gendron, F., 1997. New locality and a new kind of jadeite jade from Guatemala; rutile-quartzjadeitite.
Terra Abstracts. 9, Suppl. 1: 35.
Sorensen, S. S. and Harlow, G. E., 1998. A cathodoluminescence (CL)-guided ion and electron microprobe tour
of jadeitite chemistry and petrogenesis. Abstracts with Programs, 30, 1998 Annual Meeting, Geological Society
of America: A-60.
Sorensen, S. S. and Harlow, G.E., 1999. The geochemical evolution of jadeitite-depositing fluids. Abstracts
with Programs, 31, 1999 Annual Meeting, Geological Society of America: A-101.
Suturin, A.N. 1986. Physicochemical model of nephritization. Transactions (Doklady) of the U.S.S.R. Academy
of Sciences: Earth Science Sections. 291: 199-201.
Visser, J. M., 1946. Nephrite and chrysoprase of Silezia. Mineralogist, 14; Oregon Agate and Mineral Society:
460-462, Portland.
Wand,.W.-S., 1987. Nephrite deposits of Taiwan. In: Pacific Rim congress 87; an international congress on the
geology, structure, mineralization and economics of the Pacific Rim. Australasian Institute of Mining and
Metallurgy: 639-640, Parkville, Victoria.
Webster, R., 1975. Gems: Their Sources, Descriptions and Identification. Third Edition, Archon Books,
Shoestring Press, Inc., 931, Hamden, CT, U.S.A.
Yui, T-F., Yeh, H-W. and Lee, C. W., 1988. Stable isotope studies of nephrite deposits from Fengtian, Taiwan.
Geochimica et Cosmochimica Acta 52: 593-602.

Figure 1: World-wide nephrite occurrences


Figure 2: World-wide jadeitite occurrences



This citation is:

Harlow, G.E. and Sorensen, S.S. (2001) Jade: Occurrence and metasomatic origin — extended abstract from International Geological Congress 2000. The Australian Gemmologist 21, 7-10.

Principal author and contact:

George E. Harlow, Ph. D.
Dept. Earth and Planetary Sciences,
American Museum of Natural History
Central Park West at 79th St., NY, NY 10024-5192 U.S.A.
Phone (212)769-5378 FAX (212)769-5339
Email: gharlow@amnh.org

Second author:

Sorena S. Sorensen, Ph. D.
Department of Mineral Sciences, NHB-119
National Museum of Natural History
Smithsonian Institution
Washington, DC 20560-0119 U.S.A.
Phone (202) 357-4010 FAX (202) 357-2476
Email: sorena@volcano.si.edu

PrintView Printer Friendly Version

EmailEmail Article to Friend

Reader Comments (2)

A very interesting article, but very technical and not for the casual person. I would have to go study several other references just to completely understand what is being said here. It would be interesting to see a layman's translation of some of the above article for those not so scientifically inclined such as the beginning hobbyist, or myself for that matter.
July 17, 2010 | Unregistered CommenterBen Freeman
In short, getting cheap custom made handbags could
http://www.wholesalelinklondon.com/links-of-london-charms.html possibly be considered a intelligent notion when you can spend less loads of bucks and get two or additional for the price of one reliable bag. teens would specifically would rather pick this option as they http://www.wholesalelinklondon.com/links-of-london-sale.html are frequently style conscious and reduced on spending budget most within of the times. in the identical time, one ought getting mindful that these bags might not http://www.wholesalelinklondon.com/links-of-london-bangles.html ensure you the durability as http://www.wholesalelinklondon.com/links-of-london-sweetie.html
well as the identical remarkable since the reliable http://www.wholesalelinklondon.com/links-of-london-friendship.html handbags and could possibly place on out quickly.
April 28, 2011 | Unregistered Commenteranping

PostPost a New Comment

Enter your information below to add a new comment.
Author Email (optional):
Author URL (optional):
Post:
 
All HTML will be escaped. Hyperlinks will be created for URLs automatically.