Lamprophyllite

Lamprophyllite (named for its lustrous cleavage) is a rare, but widespread mineral Ti-silicate mineral usually found in intrusive agpasitic igneous rocks. Yellow, reddish brown, Vitreous, Pearly.[2]

Lamprophyllite
General
CategorySilicate mineral
IMA symbolLmp[1]

Lamprophyllite formula is (Sr,Ba,K,Na)2Na(Na,Fe,Mn)2Ti[Ti2O2(Si2O7)2[(O, OH,F)2 . Full isomorphic range between lampropyllite and baritollalpropyllite exist.[3]

The general crystal-chemical formula for lampropyllite-related minerals can be written as A2[(M1)(M2)2(M3)X2] [[5] L2(Si2O7)2O2], where the contents of the O and H sheets are given in square brackets in this order and A = Sr, Ba,K, Na; M1 = Na, Mn2+; M2 = Na, Mn2+, Fe2+, Ca; M3 = Ti, Mn2+, Mg, Fe3+, Fe2+; L = Ti, Fe3+; X = OH, O, F.[4]

Lamprophyllite is monoclinic, The mineral also has an orthorhombic polytype[5] Unit-cell parameters mainly depend from the cationic composition in the interlayer position A[6] The crystal structures of the lamprophyllite-related minerals are based upon HOH modules consisting of a central octahedral O sheet sandwiched between two heteropolyhedral H sheets.[7]

Lamprophyllite melts incongruently (880 °C) with formation of titanium oxides: rutile, tausonite, freudenbergite. Syntetic lamprophyllite synthesis was crystallized from melt. Tewly formed lamprophyllite show higher Sr/Ba ratioi than in equilibrium melt.[8]

Pseudobinare phase diagram lamprophyllite-nepheline

References
  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. "Lamprophyllite".
  3. Zaitsev V.A. Kogarko L.N. (2002). "Compositions of Minerals of the Lamprophyllite Group from Alkaline Massifs Worldwide". Geochemistry International. 40: 313–322.
  4. Rastsvetaeva, Ramiza K.; Chukanov, Nikita V.; Aksenov, Sergey M. (2016-12-31). "The crystal chemistry of lamprophyllite-related minerals: a review". European Journal of Mineralogy. 28 (5): 915–930. Bibcode:2016EJMin..28..915R. doi:10.1127/ejm/2016/0028-2560.
  5. Krivovichev, Sergey V.; Armbruster, Thomas; Yakovenchuk, Viktor N.; Pakhomovsky, Yakov A.; Men'shikov, Yuriy P. (2003-08-01). "Crystal structures of lamprophyllite-2M and lamprophyllite-2O from the Lovozero alkaline massif, Kola peninsula, Russia". European Journal of Mineralogy. 15 (4): 711–718. Bibcode:2003EJMin..15..711K. doi:10.1127/0935-1221/2003/0015-0711. ISSN 0935-1221.
  6. Zaitsev, V. A. (May 2005). "Numerical dependence of the unit-cell parameters of minerals of the lamprophyllite group on the cationic composition in the interlayer position". Crystallography Reports. 50 (3): 379–381. Bibcode:2005CryRp..50..379Z. doi:10.1134/1.1927593. ISSN 1063-7745. S2CID 98166023.
  7. Rastsvetaeva, Ramiza K.; Chukanov, Nikita V.; Aksenov, Sergey M. (2016-12-31). "The crystal chemistry of lamprophyllite-related minerals: a review". European Journal of Mineralogy. 28 (5): 915–930. Bibcode:2016EJMin..28..915R. doi:10.1127/ejm/2016/0028-2560.
  8. VA Zaitsev, LD Krigman, LN Kogarko (2004). "Pseudobinare phase diagram lamprophyllite-nepheline". Lithos. EMPG-X special volume.{{cite journal}}: CS1 maint: multiple names: authors list (link)


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