Ludlamite
Current inventory:  2 gems
 

  
Ludlamite is named in honor of Henry Ludlam (1824 - 1880), English mineral collector, 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:

Ludlamite Group

Varieties:

n/a

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:

[001] Perfect, [100] Indistinct

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

Other:

F

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

More Information

Mindat.org
Webmineral.com

Ludlamite is a classic phosphate mineral that produces beautiful, very collectable specimens of apple green to dark green. Faceted gems are extremely rare.

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: