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Table of Contents - Liz Fodi - Liz Fodi - Peter Tarassoff - Liz Fodi - Mike Skebo & Quintin Wight - Malcolm Back - Tony Steede - Peter Tarassoff - Tony Steede MSH Collecting Dates 2002 - Liz Fodi July 6 July 27 September 7 October 26  MSH News - Malcolm Back Additions and corrections to the last published Species list of November 15, 2001 Correct spelling of manganokhomyakovite Add natrolemoynite (see article below; no UK number) Add tsepinite-Na (see CMMA 35 #5, Nov-Dec 2001) Add vuoriyarvite-K (see article below; species originally approved as vuoriyarvite, but later changed to vuoriyarvite-K) Add UK-112, after "Finished by R.A. Gault, et al" Correct röntgenite to röntgenite-(Ce) Add clinoptilolite-K (see article below) Natrolemoynite - abstracted by Malcolm Back McDonald, A.M. and Chao G.Y. (2001). Natrolemoynite, a new hydrated sodium zirconosilicate from Mont Saint-Hilaire, Quebec: Desciption and structure determination. Canadian Mineralogist. 39, 1295-1306. Natrolemoynite ideally Na4Zr2Si10O26 · 9H2O, a new member of the lemoynite group is found in both altered and unaltered pegmatites, crosscutting nepheline syenite at the Poudrette quarry. No UK number was assigned to this mineral. The intensely altered pegmatite was originally encountered in 1964-65 when small quantities of material with lemoynite-group minerals were collected. It was intersected again in 1985, when a large number of excellent specimens were collected. The type material came from material originally collected by the late A. Vogg, probably from the 1985 find. The associated minerals are microcline, lemoynite, lepidocrocite (previously described as a "reddish-brown resinous material" (Horváth and Gault, 1990), galena, sphalerite, calcite, and pyrite. It is found in or around the interstices between coarse, intergrown crystals of microcline perthite. The crystals are bladed to prismatic, elongate parallel to [001], with maximum widths of 1 mm. and lengths of 2 mm. They typically develop in compact radial aggregates and spheres, with a maximum diameter of 4 mm. A second occurrence was recovered in a an unaltered pegmatite block recovered from the North-east corner of the quarry, on the so-called 8th level in July, 1998. Here it occurs as fine acicular sprays, <0.5 mm. in length on quartz. Associated minerals include biotite, microcline, albite, magnetite, a chlorite group. mineral, a burbankite group. mineral (remondite-(Ce)?), UK109 (a donnayite-(Y)-like mineral), zircon and pyrochlore. Natrolemoynite is colourless to white, and may have a slight pink or reddish tint due to the lepidocrocite. It has a vitreous to adamantine lustre, (the adamantine lustre most obvious with the 1998 material), is transparent to translucent, with a white streak and exhibits no fluorescence in either short- or long-wave ultraviolet light. The mineral has a Mohs hardness of 3, with perfect {100} and {010}, and a poor {001} cleavage. It is brittle with an uneven fracture. The measured density is 2.47 g/cm3, and a calculated density of 2.50 g/cm3. Natrolemoynite is monoclinic, space group C2/m, a 10.515(2), b 16.2534(4), c 9.1029(3), 105.462(2) . The dominant forms are {100}, {010} and {001} with unindexed pinacoidal-like forms present on some crystals. It is non-pleochroic, biaxial negative, 1.533(1), 1.559(1), 1.567(1) ( = 590 nm), 2Vmeas. = 63(1) , 2Vcalc. = 57(1) , dispersion weak with r and v crossed. The optical orientation is X = b, Z a = 41 in obtuse . The crystal structure was also determined and it showed that natrolemoynite is chemically and structurally related to both lemoynite and altisite. Six-membered rings of SiO4 tetrahedra are linked along [001] by ZrO6 octahedra to form a zirconosilicate framework. Channels parallel to [001] are occupied by Na and H2O. References: Horváth, L & Gault, R.A., (1990). The mineralogy of Mont Saint-Hilaire, Quebec. Mineralogical Record. 21, 284-368. Andy McDonald updates us on the following studies. UK57, the IMA proposal is just about finished and will soon be sent for approval. UK69, has been accepted, but is not yet published. UK75, is likely to remain on the shelf for quite a while longer. The crystals are very poor; Collected data on one, but the structure (near R = 10%) doesn't make a whole lot of sense. UK92, has been accepted, but is not yet published. UK99, structure has finally been solved after eight months of work! This one will be submitted for approval very soon. UK107/108, proposals are close to the IMA submission stage. Clinoptilolite-K - Tony Steede Persistence by collectors has resulted in the identification of another mineral from MSH. The story started three or four years ago when Pennsylvanian collector Dick Tillett found crystals that he did not recognize. They looked a bit like cleavelandite but exhibited strong green fluorescence under short wave UV radiation. Specimens made the rounds between his friends in an attempt to find someone who had seen something similar, without success. A specimen was sent for professional analysis – I believe that the process used was energy dispersion spectroscopy (EDS) – and the answer came back that it was likely the cleavelandite form of albite. Many collectors would have accepted this identification; how can you argue with sophisticated equipment? But some of Dick's friends were not satisfied. One of them, Ralph Thomas, asked me to take a look at a piece at the Canadian Micro Mineral Association conference at Brock University last year. In a past life (before being infected with the incurable Mont Saint-Hilaire virus) I was interested in phosphates and spent some time collecting from the pegmatites of Maine and New Hampshire where I encountered a great deal of cleavelandite. And, of course, the magic mountain has its share of this mineral. I had some trouble accepting that the one that Ralph showed me was cleavelandite and offered to give some to Dr. Andy McDonald of Laurentian University, who was at the conference. Ralph could have done it just as easily, but I am delighted to have been the conduit. We are once again indebted to Dr. McDonald. It was not an easy analysis, and I understand that he still has some misgivings about the morphology, but he is now satisfied that the mineral is clinoptilolite-K. Description: Colour: Colourless, transparent. Luster: Vitreous to slightly pearly on (010). Form: Platey, with possible twinning or stacking on (010). Cleavage: Perfect cleavage {010} Fluorescence: Strong light green (yellow-green?) short wave, nothing long wave. Matrix: Unknown, but looks very much like sodalite xenolith material. (This is a bit problematic as I do not recall any sodalite xenoliths being encountered three or four years ago). Associations: eudialyte family (probably kentbrooksite as they exhibit faint Nd spectral lines). Some of these are elongated and contain horizontal veiling; aegirine, sodalite (rough, opaque, fluorescent crystals) and tiny, white, sugar like powder; reflective, similar to struvite. Vuoriyarvite-K from Mont Saint-Hilaire - Peter Tarassoff Another mineral of the labuntsovite-nenadkevichite group has recently been identified from Mont Saint-Hilaire. Vuoriyarvite-K, ideally (K, Na)2(Nb,Ti)2Si4O12 (O,OH)2 · 4H2O, was first described, as vuoriyarvite, from the Vuoriyarvi alkaline-ultramafic complex in the Kola Peninsula, Russia (Subbotin et al., 1998; Mandarino, 2001). It is also known from the Khibiny and Lovozero alkaline complexes, Kola Peninsula, Russia, and from the Narssârssuk pegmatite, Igaliko complex, Greenland (Pekov, 2000). The Mont-Saint Hilaire vuoriyarvite-K, identified from the author's collection, has an interesting history. It was originally identified in 1969 as UK19-1 by Dr. G.Y. Chao using X-ray powder diffraction. At that time UK19-1 from the same occurrence was under investigation by Dr. Guy Perrault who considered the mineral to be a new species (Perrault et al., 1969). Although Dr. Perrault had some misgivings, it was subsequently concluded that UK19-1 was nenadkevichite which had first been described in 1955. Last year, a specimen of the UK19-1 identified by Dr. Chao was microprobed (WDS) by R.A. Gault at the Canadian Museum of Nature. Compared with other nenadkevichites from Mont Saint-Hilaire, the analysis showed a very high potassium content, approaching that of sodium on an atomic basis, although still within the accepted range for nenadkevichite. Perrault's analysis of UK19-1 had actually shown a slight excess of potassium over sodium. As recently reported in Micronews (Horváth, 2001), some nenadkevichites from Mont Saint-Hilaire have turned out to be other members of the newly defined labuntsovite group (Chukanov et al., 2002). When Dr. Igor Pekov at Moscow State University, who is involved in research on the group, opined that the newly analysed UK19-1 might in fact be a member of the vuoriyarvite series a specimen was submitted for his examination. This revealed the presence of two labuntsovite group minerals: vuoriyarvite-K, and a sodium-dominant member of the vuoriyarvite series currently under study. Dr. Perrault's original contention that UK19-1 was a then new species has proven to be correct. Two other "nenadkevichites," UK19-8 and UK19-9, are also K-dominant (Mandarino and Anderson, 1989); their true identity remains to be determined. The Mont Saint-Hilaire vuoriyarvite-K was collected from a hydrothermally-altered pegmatite vein which was exposed in the De-Mix section of the quarry in 1967 and again in 1969. It is intimately associated with the Na-dominant phase, from which it is visually indistinguishable. The minerals occur as pale pink, platy, pseudomorphic, often porous, masses up to several decimeters across, and as pale pink to pinkish white, opaque, equant, pseudohexagonal, monoclinic crystals to 0.5 mm. The crystals line tiny cavities in the platy masses or are impaled on acicular aegirine crystals. Some of the platy masses display crystal faces whose morphology, together with presence of what appears to be relict epistolite, suggests that the precursor mineral was vuonnemite. Other associated minerals include analcime, a member of the eudialyte group, albite, microcline, steacyite, yofortierite, brockite and what is apparently thornasite. This pegmatite is the original source of UK4 (steacyite), UK25 (yofortierite), and very likely, UK27 (thornasite). Large quantities of material were available when the pegmatite was exposed, and many specimens of vuoriyarvite-K and the associated phase undoubtedly reside in institutional and private collections labelled as nenadkevichite. References: Chukanov, N.V., Pekov, I.V., and Khomyakov, A.P. (2002). Recommended nomenclature for labuntsovite-group minerals. European Journal of Mineralogy, 14, 165-173. Horváth, L. (2001). Korobitsynite and tsepinite-Na from Mont Saint-Hilaire. Micronews, 35 (5), 5-6. Mandarino, J.A. (2001). New Minerals 1995-1999. Canadian Mineralogist, Special Publication 4, p. 258. Mandarino, J.A., and Anderson, V. (1989). Monteregian Treasures: The Minerals of Mont Saint-Hilaire, Quebec. Cambridge University Press, New York, p. 264. Pekov, I.V. (2000). Lovozero Massif: History, Pegmatites, Minerals. Ocean Pictures Ltd., Moscow, Russia, 484 p. Perrault, G., Vicat, J., and Sang, N. (1969). UK19-1 et UK19-2, deux nouveau silicates hydrates de niobium de Mont St-Hilaire, P.Q. Canadian Mineralogist, 10, 143-144 (abstract). Subbotin V.V., Voloshin, A.V., Pakhomovskii, Ya.A., Bakhchisaraitsev, A. Yu., Pushcharovsky, D.Yu., Rastvetaeva, R.K., and Nadezhina, T.N. (1998). Vuoriyarvite (K,Na)2(Nb,Ti)2Si4O12 (O,OH)2.4H2O -a new mineral from carbonatite of the Vuoriyarvi massif (Kola Peninsula). Doklady Rossiiskoi Akademii Nauk, 358 (4), 517-519 (in Russian). Help with Sodalite Xenolith Specimens! - Tony Steede Many rare Mont Saint-Hilaire minerals from sodalite xenoliths are being destroyed. The problem stems from several unstable minerals contained in the matrix. Look at the formulae of the following two minerals: Natrite – Na2CO3 Natron – Na2CO3 • 10H2O Obviously, these two minerals have very similar chemistry. The problem is that both are unstable. Natrite hydrates quickly to thermonatrite (Na2CO3 • H2O), while natron dehydrates very rapidly, also forming thermonatrite. Thermonatrite is the white efflorescence that forms on the surface of many sodalite xenolith specimens as they sit in collections. As the reaction continues, the specimen often falls apart, ruining many of the rare minerals only found in the sodalite xenoliths. If one adds moisture it will encourage the natrite to thermonatrite reaction while an attempt to reduce humidity will encourage the natron to thermonatrite reaction. Natrophosphate (Na7(PO4)2F • 19H2O) may pose another problem. It is reported as "…0.5-2mm, colorless to frosty-white, transparent to turbid, highly modified octahedra and dodecahedra, in small cavities in sodalite xenoliths." (Lázló Horváth and Robert A. Gault (1990), The Mineralogy of Mont Saint-Hilaire Quebec. The Mineralogical Record, vol. 21 #4). Dr. Igor Pekov (Lovozero Massif: History, Pegmatites, Mineralogy, Ocean Pictures Ltd., Russia (2000)) states "Thermonatrite is the product of aggressive effect of atmospheric carbon dioxide upon many unstable alkali-rich minerals; so, together with dorfmanite and nahpoite, it replaces natrophosphate and precipitates as efflorescence….". I have not heard whether Mont Saint-Hilaire natrophosphate alters in collection settings to thermonatrite (or dorfmanite and nahpoite, both of which are found on MSH sodalite xenoliths). If anyone can suggest ways of preventing these reactions they would be doing the collecting community a great service by getting in touch with me or the editor of Micronews.
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