| Lorenzenite | |
|---|---|
 Doubly terminated crystal of Lorenzenite, 2.5 cm tip to tip, fromLovozero Massif,Kola Peninsula, Russia | |
| General | |
| Category | Silicate mineral |
| Formula | Na2Ti2[O3|Si2O6] |
| IMA symbol | Lrz[1] |
| Strunz classification | 9.DB.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H–M Symbol: (2/m 2/m 2/m) |
| Space group | Pbcn |
| Unit cell | a = 8.71, b = 5.23 c = 14.48 [Å]; Z = 4 |
| Identification | |
| Color | Pale purple-brown, pale pink to mauve, brown to black |
| Crystal habit | Equant, bladed, prismatic, to needlelike crystals; fibrous, felted, lamellar aggregates |
| Cleavage | Distinct/good on {010} |
| Fracture | Irregular/uneven |
| Mohs scale hardness | 6 |
| Luster | Adamantine, vitreous, sub-metallic, dull |
| Streak | White to pale brown |
| Diaphaneity | Transparent, opaque |
| Specific gravity | 3.42 – 3.45 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.910 – 1.950 nβ = 2.010 – 2.040 nγ = 2.030 – 2.060 |
| Birefringence | δ = 0.120 |
| Pleochroism | Weak |
| 2V angle | Measured: 38° to 41° |
| Ultravioletfluorescence | Pale yellow to dull green under SW UV |
| References | [2][3][4] |
Lorenzenite is a rare sodium titaniumsilicate mineral with the formulaNa2Ti2Si2O9 It is anorthorhombic mineral, variously found as colorless, grey, pinkish, or brown crystals.
It was first identified in 1897 in rock samples from Narsarsuk,Greenland.[3] In 1947 it was discovered to be the same as the mineralramsayite (now a synonym of lorenzenite), discovered in the 1920s in theKola peninsula ofRussia. It is also found in northernCanada.
It occurs innepheline syenites andpegmatites in association withaegirine,nepheline,microcline,arfvedsonite,elpidite,loparite,eudialyte,astrophyllite, mangan-neptunite,lavenite,rinkite,apatite,titanite andilmenite.[2]
It was named in honor of Danish mineralogistJohannes Theodor Lorenzen (1855–1884).[3]
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