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Ludwigite  
Current inventory:  0 gems
 

  
Ludwigite was named to honor Ernst Ludwig (1842–1915), Austrian Professor of Chemistry, University of Vienna, Vienna, Austria, who analyzed the original material.

Discovered in 1874;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Mg₂Fe³⁺BO₅

Magnesium Iron Borate

Molecular Weight:

195.26 gm

Composition:

Magnesium

24.89 %

Mg

41.28 %

MgO

Iron

28.60 %

Fe

40.89 %

Fe₂O₃

Boron

5.54 %

B

17.83 %

B₂O₃

Oxygen

40.97 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Borates

Strunz 8th Ed. ID:

5/G.04-10

Nickel-Strunz 10th Ed. ID:

6.AB.30

6 : BORATES
A : Monoborates
B : BO₃, with additional anions; 1(D) + OH, etc.

Related to:

Ludwigite Group. Ludwigite-Vonsenite Series. The magnesium analogue of Vonsenite. Isostructural with Vonsenite.

Varieties:

Alumoludwigite

Synonyms:

Collbranite, Magnesioludwigite

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals are unterminated, fibrous, curved, to 20 cm; commonly in fanlike to felted aggregates.

Twinning:

None

Physical Properties

Cleavage:

None observed

Fracture:

Fibrous

Tenacity:

Tough

Moh's Hardness:

5.0 - 5.5

Density:

3.80 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

• Weakly ferromagnetic, probable.

• Slowly soluble in acids. Alters to Limonite.

Optical Properties

Color:

Dark Olive-Green to Pitch Black

Transparency:

Opaque to Sub-Translucent. Translucent only in thin fragments and rims of crystals.

Luster:

Silky, Metallic

Refractive Index:

1.83 - 2.03  Biaxial ( + )

Birefringence:

0.1400 - 0.1800

Dispersion:

Extreme; r >> v

Pleochroism:

X = Y = dark green; Z = dark reddish brown

Anisotrophism:

Strong; yellowish brown to bluish violet gray

Other:

Bireflectance: Pinkish gray to dark greenish gray

Occurances

Geological Setting:

Typically formed in magnesian iron skarn and contact metamorphic deposits.

Common Associations:

Magnetite, Forsterite, Clinohumite, Vonsenite, Szaibélyite.

Common Impurities:

Al

Type Locality:

Ocna de Fier (Vaskö-Moravita; Vaskö-Moravicza; Eisenstein), Ocna de Fier-Dognecea District, Banat Mts, Caras-Severin County, Romania

Year Discovered:

1874

View mineral photos:

Ludwigite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Ludwigite is a relatively rare magnesium iron borate mineral that is rarely mentioned in the gem trade. Although there are opaque black, metallic faceted Ludwigite gems available as curiosities for collectors of the unusual, the most common occurance of Ludwigite as a gem is as dark, olive-green Ludwigite inclusions in Peridot from Pakistan. These gems can be so densely included with the fine, fibrous, dark green Ludwigite needles that a normally bright green Peridot can be very dark green.

There are numerous localities for finding Ludwigite, some with large amounts. From the Luliana mine, Ocna de Fier Morávicza; Vaskö), Romania. At the Brosso mine, northwest of Ivrea, Torino, Italy. From Broadford, Isle of Skye, Inverness-shire, Scotland. In the Nordmark district, Värmland, Sweden. In Russia, at the Tazheran massif, west of Lake Baikal; large crystals from Titovskoye, Sakha. In the Gole Gohar iron deposit, Bafq district, Iran. In the USA, from the Pomeroy mine, Anaconda, Deer Lodge County, and at Philipsburg, Granite County, Montana; from the Crestmore quarry, Riverside County, California; at the Mountain Lake mine, Big Cottonwood district, Salt Lake County, Utah. In Canada, in the York River tactite zone, Bancroft, Ontario; from the Cross quarry, near Wakefield, Quebec. In the Hol Kol Au–Cu mine, about 75 km southeast of Pyongyang, Suan County, North Korea.
 

  
Ludwigite gems for sale:

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