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Doubly terminated crystal of Lorenzenite, 2.5 cm tip to tip, from Lovozero Massif, Kola Peninsula, Russia
CategorySilicate mineral
(repeating unit)
Strunz classification9.DB.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H–M Symbol: (2/m 2/m 2/m)
Space groupPbcn
Unit cella = 8.71, b = 5.23
c = 14.48 [Å]; Z = 4
ColorPale purple-brown, pale pink to mauve, brown to black
Crystal habitEquant, bladed, prismatic, to needlelike crystals; fibrous, felted, lamellar aggregates
CleavageDistinct/good on {010}
Mohs scale hardness6
LusterAdamantine, vitreous, sub-metallic, dull
StreakWhite to pale brown
DiaphaneityTransparent, opaque
Specific gravity3.42 - 3.45
Optical propertiesBiaxial (-)
Refractive indexnα = 1.910 - 1.950 nβ = 2.010 - 2.040 nγ = 2.030 - 2.060
Birefringenceδ = 0.120
2V angleMeasured: 38° to 41°
Ultraviolet fluorescencePale yellow to dull green under SW UV

Lorenzenite is a rare sodium titanium silicate mineral with the formula Na2Ti2Si2O9 It is an orthorhombic mineral, variously found as colorless, grey, pinkish, or brown crystals.

It was first identified in 1897 in rock samples from Narsarsuk, Greenland.[2] In 1947 it was discovered to be the same as the mineral ramsayite (now a synonym of lorenzenite), discovered in the 1920s in the Kola peninsula of Russia. It is also found in northern Canada.

It occurs in nepheline syenites and pegmatites in association with aegirine, nepheline, microcline, arfvedsonite, elpidite, loparite, eudialyte, astrophyllite, mangan-neptunite, lavenite, rinkite, apatite, titanite and ilmenite.[1]

It was named in honor of Danish mineralogist Johannes Theodor Lorenzen (1855–1884).[2]