Ludlamite Value, Price, and Jewelry Information


LUDLAMITE: Idaho (~0.5). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Ludlamite has a lovely green color but is too soft for wear. Large crystals are known from only a few localities, and cut stones are extremely rare.

Ludlamite Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Ludlamite Information

DataValue
NameLudlamite
Crystallography Monoclinic. Crystals tabular, wedgeshaped; also granular.
Colors Apple green, dark green, pale green, greenish white, colorless.
Luster Vitreous.
Fracture Conchoidal; brittle.
Hardness 3.5.
Specific Gravity 3.19.
Birefringence 0.038-0.044.
Cleavage Perfect 1 direction.
Stone SizesLudlamite is seldom cut, and transparent material is always small. The potential may exist for 5-10 carat gems, but most are in the 1-2 carat or smaller range.
Luminescence Not diagnostic.
Spectral Not diagnostic.
FormulaFe3(PO4)2 · 4H2O.

Streak: Pale greenish white.

Optics: a = 1.650-1.653; β= 1.667-1.6 75; γ= 1.688-1.697.

Biaxial (+), 2V= 82°.

Occurrence: A secondary mineral in the oxidized zone of ore deposits; also due to the alteration of primary phosphates in granite pegmatites.

New Hampshire.

Cornwall, England; Hagendorf, Germany.

Blackbird Mine, Lemhi County, Idaho: fine crystals up to ½ inch across.

South Dakota: crystalline masses to 12 inches in diameter with 7 mm crystals at Keystone.

Comments: Ludlamite has a lovely green color but is too soft for wear. Large crystals are known from only a few localities, and cut stones are extremely rare.

Name: After Henry Ludlam, of London, English mineralogist and collector.