| 词条 | Ludwigite |
| 释义 |
| name = Ludwigite | category = Borate mineral | boxwidth = | boxbgcolor = | image = Ludwigite-242641.jpg | imagesize = 260px | caption = Radial aggregates of lustrous, black, metallic, acicular ludwigite crystals to 0.5 cm, from Alta Stock, Salt Lake County, Utah, USA. | formula = Mg2Fe3+BO5 | molweight = 195.26 g/mol | strunz = 6.AB.30 | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pbam | unit cell = a = 9.26, b = 12.26 c = 3.05 [Å]; Z = 4 | color = Pitch-black, olive-black | habit = Massive - fibrous commonly in fanlike to felted aggregates | cleavage = [001] Perfect | fracture = Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments. | mohs = 5.5 | luster = Silky to submetallic | refractive = nα = 1.830 - 1.850 nβ = 1.830 - 1.850 nγ = 1.940 - 2.020 | opticalprop = Biaxial (+) | birefringence = δ = 0.110 - 0.170 | pleochroism = X = Y = dark green; Z = dark reddish brown | 2V = Measured: 20° to 45° | streak = greenish black | gravity = 3.6 - 3.8 | melt = | fusibility = | diagnostic = | solubility = Slowly soluble in acid | diaphaneity = Opaque, translucent in thin fragments | alteration = limonite | references = [1][1] }} 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.[1] It forma a solid solution series with the iron(II)-iron(III) borate mineral vonsenite.[1] 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] References1. ^1 Handbook of Mineralogy 2. ^1 2 Ludwigite at mindat {{-}}{{Commons category}}{{mineral-stub}} 4 : Magnesium minerals|Iron minerals|Borate minerals|Orthorhombic minerals |
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