Ludwigite
(repeating unit)Mg2Fe3+BO5 IMA symbol Ldw[1] Strunz classification 6.AB.30 Crystal system Orthorhombic Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m) Space group Pbam Unit cell a = 9.26, b = 12.26
c = 3.05 [Å]; Z = 4 Identification Formula mass 195.26 g/mol Color Pitch-black, olive-black Crystal habit Massive – fibrous commonly in fanlike to felted aggregates Cleavage [001] Perfect Fracture Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments. Mohs scale hardness 5.5 Luster Silky to submetallic Streak Greenish black Diaphaneity Opaque, translucent in thin fragments Specific gravity 3.6 – 3.8 Optical properties Biaxial (+) Refractive index nα = 1.830 – 1.850 nβ = 1.830 – 1.850 nγ = 1.940 – 2.020 Birefringence δ = 0.110 – 0.170 Pleochroism X = Y = dark green; Z = dark reddish brown 2V angle Measured: 20° to 45° Solubility Slowly soluble in acid Alters to limonite References [2][3]
H-M symbol: (2/m 2/m 2/m)
c = 3.05 [Å]; Z = 4
Ludwigite is a magnesium-iron borate mineral: Mg2FeBO5.
Ludwigite typically occurs in magnesian iron skarn and other high temperature contact metamorphic deposits. It occurs in association with magnetite, forsterite, clinohumite and the borates vonsenite and szaibelyite.[3] It forms a solid solution series with the iron(II)-iron(III) borate mineral vonsenite.[2]
It was first described in 1874 for an occurrence in Ocna de Fier, Banat Mountains, Caraș-Severin County, Romania and named for Ernst Ludwig (1842–1915), an Austrian chemist at the University of Vienna.[2]
References
Wikimedia Commons has media related to Ludwigite.
- ^ 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.
- ^ a b c Ludwigite on Mindat.org
- ^ a b Handbook of Mineralogy
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