Adamite
Current inventory:  1 gem
 

  
Adamite was named in honor of Gilbert-Joseph Adam (1795–1881), French mineralogist, who supplied the first specimens.

Discovered in 1866.  IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Zn₂(AsO₄)(OH)

Zinc Arsenate Hydroxide

Molecular Weight:

286.71 gm

Composition:

Zinc

45.61 %

Zn

56.78 %

ZnO

Arsenic

26.13 %

As

40.08 %

As₂O₅

Hydrogen

0.35 %

H

3.14 %

H₂O

Oxygen

27.90 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/B.06-30

Nickel-Strunz 10th Ed. ID:

8.BB.30

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H₂O
B : With only medium-sized cations, (OH, etc.):RO₄ about 1:1

Related to:

Olivenite Group. Adamite-Olivenite Series. The orthorhombic dimorph of Paradamite. Isostructural with Olivenite and Libethenite.

Members of Group:

Olivenite Group: Adamite, Eveite, Libethenite, Olivenite, Paraadamite, Tarbuttite, Zincolibethenite, Zincolivenite

Varieties:

Alumino Adamite, Cobaltoan Adamite, Cuprian Adamite (Cuproadamite), Manganoan Adamite (Manganadamite), Nickeloan Adamite

Synonyms:

Adamite (of Friedel)

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals are typically elongated, to 8 cm, may be tabular or equant; many other forms, usually in radial aggregates, fanlike rosettes, or crystalline crusts.

Twinning:

n/a

Physical Properties

Cleavage:

Good on {101}, Poor on {010}

Fracture:

Irregular, Uneven to Subconchoidal

Tenacity:

Very Brittle

Moh's Hardness:

3.5

Density:

4.32 - 4.38 (g/cm³)

Luminescence:

May fluoresce and phosphoresce lemon-yellow or bright green under SW and LW UV.

Radioactivity:

Not Radioacitve

Optical Properties

Color:

Pale yellow, honey-yellow, brownish yellow, reddish; rarely white, colorless, blue, pale green to green, may be zoned; bright green (cuprian); bright pink, rose, or purple (cobaltian); in transmitted light, colorless or faintly tinted.

Transparency:

Transparent to Translucent

Luster:

Vitreous, Resinous

Refractive Index:

1.708 - 1.773  Biaxial ( +/- )

Birefringence:

0.055

Dispersion:

Strong; r > v  or  r < v

Pleochroism:

Weak; in pale colors if cuprian or cobaltian

Occurances

Geological Setting:

A secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits.

Common Associations:

Smithsonite, Hemimorphite, Scorodite, Olivenite, Limnoite, Calcite, Quartz, Fe–Mn oxides

Common Impurities:

Cu, Mn

Type Locality:

Chañarcillo, Copiapó Province, Atacama Region, Chile

Year Discovered:

1866

View mineral photos:

Adamite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Adamite is a rare zinc phosphate mineral that belongs to the Olivenite Group of minerals that also includes Tarbuttite. It is a secondary mineral found in zinc deposits containing arsenic-bearing minerals. Adamite is very popular among collectors of fluorescent minerals because of its bright green fluorescence under short wave UV light. Adamite is isostructural with the minerals Olivenite and Libethenite. This means they share the same crystal symmetry and similar crystal shapes.

There are several varieties of Adamite that are based on additional chemicals added to the Adamite formula. These are Alumino Adamite, Cobaltoan Adamite, Cuprian Adamite (Cuproadamite), Manganoan Adamite (Manganadamite), Nickeloan Adamite. Of these, I have only found two that have been faceted; Cuprian Adamite and Manganoan Adamite.

Although there are many sources of Adamite mineral specimens, there has been only one source of gem quality crystals; the Ojuela Mine, Mapimí, Mun. de Mapimí, Durango, Mexico. There have been some beautiful, deep green crystals found at the Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia, but these are generally too small for faceting.
 

  
Adamite gems for sale: