Ludwigite

.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent;color:inherit}.mw-parser-output .infobox-3cols-child{margin:-3px}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}

Ludwigite
Radial aggregates of lustrous, black, metallic, acicular ludwigite crystals to 0.5 cm, from Alta Stock, Salt Lake County, Utah, USA.
Borate mineral
Mg2Fe3+BO5
Ldw
6.AB.30
Orthorhombic
Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Pbam
a = 9.26, b = 12.26 c = 3.05 [Å]; Z =
195.26 g/mol
Pitch-black, olive-black
Massive – fibrous commonly in fanlike to felted aggregates
[001] Perfect
Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
5.5
Silky to submetallic
Greenish black
Opaque, translucent in thin fragments
3.6 – 3.8
Biaxial (+)
nα = 1.830 – 1.850 nβ = 1.830 – 1.850 nγ = 1.940 – 2.020
δ = 0.110 – 0.170
X = Y = dark green; Z = dark reddish brown
Measured: 20° to 45°
Slowly soluble in acid
limonite

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. It forms a solid solution series with the iron(II)-iron(III) borate mineral vonsenite.

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.

Ludwigite needles and sprays as inclusions in a peridot crystal from Sapat Gali, Kohistan District, Pakistan. Size 2.8 x 2 x 1.1 cm.

.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);color:inherit;display:flow-root}.mw-parser-output .infobox .side-box{font-size:100%}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:640px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}

@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{filter:invert(1)brightness(55%)contrast(250%)hue-rotate(180deg)}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{filter:invert(1)brightness(55%)contrast(250%)hue-rotate(180deg)}}

.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}body.skin-vector-2022 .mw-parser-output .reflist-columns-2{column-width:27em}body.skin-vector-2022 .mw-parser-output .reflist-columns-3{column-width:22.5em}.mw-parser-output .references[data-mw-group=upper-alpha]{list-style-type:upper-alpha}.mw-parser-output .references[data-mw-group=upper-roman]{list-style-type:upper-roman}.mw-parser-output .references[data-mw-group=lower-alpha]{list-style-type:lower-alpha}.mw-parser-output .references[data-mw-group=lower-greek]{list-style-type:lower-greek}.mw-parser-output .references[data-mw-group=lower-roman]{list-style-type:lower-roman}.mw-parser-output div.reflist-liststyle-upper-alpha .references{list-style-type:upper-alpha}.mw-parser-output div.reflist-liststyle-upper-roman .references{list-style-type:upper-roman}.mw-parser-output div.reflist-liststyle-lower-alpha .references{list-style-type:lower-alpha}.mw-parser-output div.reflist-liststyle-lower-greek .references{list-style-type:lower-greek}.mw-parser-output div.reflist-liststyle-lower-roman .references{list-style-type:lower-roman}

.mw-parser-output .asbox{position:relative;overflow:hidden}.mw-parser-output .asbox table{background:transparent}.mw-parser-output .asbox p{margin:0}.mw-parser-output .asbox p+p{margin-top:0.25em}.mw-parser-output .asbox-body{font-style:italic}.mw-parser-output .asbox-note{font-size:smaller}.mw-parser-output .asbox .navbar{position:absolute;top:-0.75em;right:1em;display:none}.mw-parser-output :not(p):not(.asbox)+style+.asbox,.mw-parser-output :not(p):not(.asbox)+link+.asbox{margin-top:3em}