Ludlamite
Current inventory: 1 gem
 

  
Ludlamite was named in 1877 by Nevil Story Maskelyne (1823–1911) and Frederick Field (1826-1885) in honor of English mineral collector Henry Ludlam (1824-1880), London, England.

Discovered in 1877; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Fe²⁺,Mg,Mn²⁺)₃(PO₄)₂ • 4H₂O

Hydrated Iron Magnesium Manganese Phosphate

Molecular Weight:

400.88 gm

Composition:

Magnesium

5.46 %

Mg

9.05 %

MgO

Manganese

4.11 %

Mn

5.31 %

MnO

Iron

25.08 %

Fe

32.26 %

FeO

Phosphorus

15.45 %

P

35.41 %

P₂O₅

Hydrogen

2.01 %

H

17.98 %

H₂O

Oxygen

47.89 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/C.10-10

Nickel-Strunz 10th Ed. ID:

8.CD.20

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H₂O
D : With only medium-sized cations, RO₄:H₂O = 1:2

Related to:

Isostructural with Metaswitzerite, Sterlinghillite, Switzerite.

Varieties:

None

Synonyms:

Lehnerit (of Müllbauer)

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As crystals, usually tabular, to 9 cm, may be in parallel groups; granular, massive.

Twinning:

None

Physical Properties

Cleavage:

Perfect on [001], Indistinct on [100]

Fracture:

Conchoidal

Tenacity:

Slightly brittle

Moh's Hardness:

3.5

Density:

3.12 - 3.19 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioacitve

Other:

Diamagnetic. Soluble in acids.

Optical Properties

Color:

Apple-Green to bright Green; nearly Colorless in transmitted light

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on cleavage [001]

Refractive Index:

1.650 - 1.697  Biaxial ( + )

Birefringence:

0.038 - 0.044

Dispersion:

Perceptible; r > v

Pleochroism:

None

Occurances

Geological Setting:

In complex granite pegmatites, a common hydrothermal alteration product of earlier phosphates, formed under reducing conditions.

Common Associations:

Apatite, Phosphoferrite, Triphylite, Triplite, Triploidite (Hagendorf, Germany); Fairfieldite, Siderite, Vivianite, Whitlockite (Palermo #1 mine, New Hampshire, USA).

Common Impurities:

n/a

Type Locality:

Wheal Jane (Falmouth Consolidated; Wheal Whidden; Wheal Nangiles; Wheal Tremayne), Baldhu, Camborne - Redruth - St Day District, Cornwall, England, UK

Year Discovered:

1877

View mineral photos:

Ludlamite Mineral Photos and Locations

Unusual Gem Categories

Magnetic Gems (diamagnetic)

More Information

Mindat.org
Webmineral.com

Ludlamite is a phosphate mineral that produces beautiful specimens characterized by bright, apple green groups of crystals that typically form as sprays of radiating, jaggedly pointed, crystals that resemble sheaves of wheat.

Ludlamite is unusual in that it is a diamagnetic mineral. Diamagnetism is a form of magnetism where certain minerals are repelled by an externally applied magnetic field, and form internal induced magnetic fields in the direction opposite to that of the applied magnetic field. In contrast with this behavior, some minerals, such as Xenotime, are paramagnetic. Paramagnetism is a form of magnetism where certain minerals are attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field.

Ludlamite was named in 1877 by English geologist Nevil Story Maskelyne (1823–1911) and English chemist Frederick Field (1826-1885) in honor of their friend, English mineral collector Henry Ludlam (1824-1880), London, England. Ludlamite was first described in 1877 for an occurrence at the Wheal Jane Mine, St. Day District, Cornwall, England.

There are only a few locations for facetable crystals. These include the Wheal Jane Mine, Truro, Cornwall, England (the Type Locality); Morococala and Huanuni, Oruro, Bolivia; Rapid Creek, Yukon Territory, Canada; Hagendorf, Bavaria, Germany; San Antonio mine, Santa Eulalia district, Chihuahua, Mexico; the Blackbird mine, Lemhi County, Idaho, USA; the Palermo #1 mine, North Groton, Grafton County, New Hampshire; and Custer County, South Dakota, USA.
 

  
Ludlamite gems for sale: