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Download the Scanned American Mineralogist, Volume 74, pages 927-933, 1989 Grandreefite,pseudograndreefite, laurelite, and aravaipaite:Four new minerals from the Grand Reef mineoGraham County, Arizona AurHoNv R. K,clvrpr Mineralogy Section,Natural History Museum of Los AngelesCounty, 900 Exposition Blvd., Los Angeles,California 90007, U.S.A. Pnrn J. DUNN Department of Mineral Sciences,Smithsonian Institution, Washington, D.C. 20560, U.S.A. EucnNB E. Foom U.S. Geological Survey, Mail Stop 905, Denver Federal Center, Lakewood, Colorado 80225, U.S.A. AssrRAcr Four new lead fluoride minerals are describedfrom the Grand Reef mine, Laurel Can- yon, Aravaipa mining district, Graham County, Arizona. They occur together in a vug surrounded by layers of quartz, fluorite, and galena.The new minerals are interpreted as resulting from the reaction ofsupergene solutions with galenaand fluorite. Grandreefite,Pb2SO4F2, is orthorhombic,a : 4.439(4),b : 13.575(13), c : 4.333,1)L, V : 261.1(4)A', spacegrorry 1222, Z: 2.Il occurs as colorlessprismatic crystals striated parallelto [001], with a densityof 7.0(l) g/cm3(meas.),7 .15 g/crn3(calc.). Grandreefrte is biaxial (+), very small2V, with weak dispersion,r > y, d : 1.872(5),B : 1.873(5),7 : 1.897(5);orientation is X: c, Y : a, Z : b. The compositionis PbO 82.9, SO313.8, F 7.1, sum 103.8,less O = F 3.0, total 100.8wt0/0. Grandreefite is isostructual with IarOrSOo, basedon layers of the B-PbR (fluorite) structure parallel to (010) with SOogroups between layers. Pseudograndreefite,PbuSOoF,o, is orthorhombic, a : 8.5182(5), b : 19.5736(ll), c : 8.4926(5)A, V: 1416.0(l)Ar, spacegrotp F222,2: 4.It occursas colorlesssquare crystalstabular on {010}, with a densityof 7.0(l) g,/cm3(meas.), 7,08 g/cm3(calc.). Pseu- dograndreefiteis biaxial (+),2V: 30(3)', with strongdispersion, r > v, d : 1.864(5),0 : 1.865(5),r : 1.873(5);orientation is X: c, Y : L, Z : b. The composition is PbO 84.9, SO34.7,F 13.1,sum 102.7,less O = F 5.5, total 97.2wto/o.The structureof pseu- dograndreefiteis very similar to that ofgrandreefite. Laurelite,Pb(F,Cl,OH)r, is hexagonal,a: 10.252(9),c : 3.973(l) A, y:36t.1(6) A', spacegroup P6, P6, or P6/m, Z: 6.It occursas colorlessneedles with a densityof 6.2(l) g/cm3(meas.), 6.52 g/cm3(calc.). Laurelite is uniaxial (+), with or: L903(5),e : 1.946(5). The composition is Pb 82.0, F 13.0, Cl 3.6, OH 0.9, total 99.5 wtol0.The structureof laurelite is probably related to that of a-PbFr. Aravaipaite,Pb3AlFe.HrO, is triclinic, with a : 5.842(2),b : 25.20(5),c : 5.652Q)A, a:93.84(4),0:90.14(4),r: 85.28(4)",V:827(2) A', spacegroupPl ot Pl',2:4.Ir occursas colorlessthin plates with perfect micaceous{010i cleavageand a density of 6.37 g/cm3 (calc.). Aravaipaite is biaxial (-), 2V: 70(3)", with strong dispersion, r < v, ot : 1.678(2)'P: 1.690(2),7: 1.69a(2);Euler angles are Q: 67",0: 6Q.,0:76'.The compositionis Pb 73.8, Al 3.6, F 21.0, HrO 3.0, total 101.4wt0/0. The structureof ara- vaipaite may be related to that of p-PbF, with layers of the B-PbF2structure parallel to {010} and Al(F,HrO) octahedrabetween layers. IurnonucrroN ing the past 25 years, the mine has become well known among mineral collectors for a variety of rare minerals. The Grand Reef mine is situated in Laurel Canyon, The most notable of these is linarite, which has been about 6 km northeast of Klondyke, in the Aravaipa min- found in well-formed crystalsup to 5 cm in length. Jones ing district of Graham County, Aizona. The mine ex- (1980) provided an overview ofthe history, geology,and ploits a small epithermallead-copper-silver deposit, which mineralogy of this deposit. is hosted by a silicified breccia. The breccia is highly re- During the course of a detailed mineralogic and para- sistant, forming a precipitous clifl locally known as the geneticstudy of the Grand Reef mine, Mr. William Besse "reef," from which the name of the mine is derived. Dur- (Besse,l98l) obtained an unusual specimen,which had 0003404x/89/0708-0927$02.00 927 928 KAMPF ET AL.: FOUR NEW MINERALS FROM GRAND REEF MINE, ARIZONA subsequently provided for examination by its current owner, Mr. ks Presmyk of Mesa, Arizona. The two spec- imens were discovered to be portions of the same vug. To date these are the only specimensknown to contain any of these new minerals. Fragments of rock trimmed from the second specimen were also provided. A block of matrix measuring27 x 25 x I 5 cm was reconstructed from thesefragments and the two vug sections. The matrix is typical of the mineralization found in the bench area of the Grand Reef mine. Veins of galena fol- low irregular fracturesin the breccia,and minor amounts of copper sulfides associatedwith the galena are altered principally to linarite and caledonite. The galena shows lesseralteration to anglesite.The vug containing the new Fig. l. Crystaldrawing of grandreefite. minerals occupiesthe center of what was evidently once an interstice between breccia blocks. Although a portion been recoveredin 1980 by Mr. Wayne Thompson under of the rock surrounding the vug is missing, it is clear that the auspices of Southwestern Mineral Associates. Mr. the vug was completely surrounded by galena.An irreg- Bessebrought the specimento the attention of one of us ular and incomplete layer of fluorite is found inside the (A.R.K.) with the observation that it might contain two galena,followed by a complete layer of quartz surround- minerals new to science.In the course of the present in- ing the quartz-lined vug. Anglesite fills fractures in the vestigation, these two minerals, as well as two others on quarlz. A completely filled pocket surrounded by galena the same specimen,were determined to be new. The four and containing only massive fluorite occurs a few centi- new minerals are named grandreefite,pseudograndreefite, meters away from the vug. laurelite, and aravaipaite. Grandreefite is named for the Isolated pocketsin galena,sometimes containing vugs, Grand Reef mine. Pseudograndreefiteis named for its are typical of the bench areaof the Grand Reef mine, and close similarity to grandreefite in physical properties, the mineralization in thesepockets is often quite distinct composition, and structure. Laurelite is named for Laurel from that in the adjacent portions ofthe oxidation zone. Canyon in which the Grand Reef mine is situated. Ara- Mr. Wayne Thompson (personal communication, 1988) vaipaite (iir d vt' pi It) is named for the Aravaipa mining has consideredthe vug containing the four new minerals district in which the mine is located. to be an example of such an occuffence. The speciesand the nameswere approved by the Com- (PbrSOlFr) mission on New Minerals and Mineral Names, IMA, prior Gn-q.NonnnrrrE to publication. The type specimen containing all four Appearanceand physical properties speciesis deposited at the Natural History Museum of The only crystal of grandreefiteon the type specimen Los AngelesCounty (cat. no. 25414). measwes 1.5 x 3 x 4 mm parallel to the F001, [010], and [001] cell directions, respectively. The characleiza- Gnor,ocrc AND MrNERALocrc sETTTNG tion of the mineral used fragments removed from this The ore at the Grand Reef mine was emplaced in a crystal, which is prismatic and striated parallel to [001]. heavily brecciated,nearly vertical fault zone. The breccia, The forms {120}, {130}, {2931,{293}, and {l0l} were consistingof rhyolite and schist fragments,has been silic- observed and are depicted in Figure l. Two bladelike ified and contains specular hematite and fluorite as the crystals of grandreefiteon the second specimen reach 7 principal gangueminerals. The most prevalent primary mm in length. ore mineral is galena, with chalcopyrite, argentite, and Grandreefite is colorless and has a white streak. It is pyrite being present in lesser amounts. Chalcocite, co- transparentwith a subadamantineluster. No fluorescence vellite, silver, and copper were products ofsupergeneen- in ultraviolet light was detected. The Mohs hardnessis richment. In addition to the four new minerals described approximately 2Yz.The mineral is brittle with a conchoi- here,Besse (1981) listed 25 other minerals,most of which dal fracture, and no cleavagewas detected.The density, have resulted from oxidation. measuredon a Berman balanceusing 3.43 mg of sample, In 1969a benchwas blastednear the top ofthe "reef' is 7.0(l) g/cm3;the calculateddensity is 7.15 g/cm3. just south ofa vertical stope known as the "glory hole." The area of this bench has produced most of the mine's Opticat properties well-crystallized oxidation minerals, predominantly sul- The optical properties of grandreefitewere determined fates. The type specimen of the four new minerals was by immersion using a Supper spindle stage. Over the found in this area. courseof a few minutes, the crystal surfacesbecame frost- The type specimenmeasures l0 x 7 x 4 cm, and the ed becauseof reaction with the high-index immersion vug containing the new minerals is about 2 x 1.5 x 0.5 liquids. This required that observationsbe made rapidly cm. A second specimenwith a 5 x 2 x 1.5 cm vug was and may have contributed to experimental error. KAMPF ET AL.: FOUR NEW MINERALS FROM GRAND REEF MINE, ARIZONA 929 Tlele 1. X-ray powder-diffractiondata for grandreefite d 10 6.73 6.78 020 10 1.581 1 581 260 JU 4.20 4.21 110 25 1.545 1.545 202 z3 4.10 4.11 011 <5 1.508 1.506 222 10 3.382 3.389 040 5 1.468 1.467 310 100 3.159 3.162 130 1 426 190 20 1.424 90 3.116 3 120 031 1.422 091 80 3.084 3 090 101 1.403 330 30b 1.401 <5 2.810 2.811 121 1.396 301 RN 2.281 2.283 141 10 1.377 1.381 271 2254 2.259 060 1.370 033 30 2209 2213 200 50b 1.370 1.370 172 30 2 158 2157 002 1.368 103 5 2 101 2104 220 10 1.291 1.291 341 2.058 2.056 022 1.275 zoz 25b 1.274 Fig.
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