Roselite
Current inventory:  0 gems, (1 sold)
 

  
Roselite is named in honor of Gustav Rose (1798 - 1873), professor of mineralogy at the University of Berlin, Germany.

Discovered in 1824; IMA status: Valid (pre-IMA; Grandfathered).

Chemistry

Chemical Formula:

Ca₂(Co,Mg)(AsO₄)₂ • 2(H₂O)

Hydrated Calcium Cobalt Magnesium Arsenate

Molecular Weight:

444.30 gm

Composition:

Calcium

18.04 %

Ca

25.24 %

CaO

Magnesium

1.37 %

Mg

2.27 %

MgO

Cobalt

9.95 %

Co

12.65 %

CoO

Arsenic

33.73 %

As

51.73 %

As₂O₅

Hydrogen

0.91 %

H

8.11 %

H₂O

Oxygen

36.01 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/C.17-100

Nickel-Strunz 10th Ed. ID:

8.CG.10

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H₂O
G : With large and medium-sized cations, RO₄:H₂O = 1:1

Related to:

Roselite Group. Roselite-Wendwilsonite Series. The monoclinc dimorph of β-Roselite. The cobalt analogue of Wendwilsonite. Isostructural with Brandtite.

Members of Group:

Roselite Group: Brandtite, Kröhnkite, Roselite, Rruffite, Wendwilsonite, Zincroselite. Closely related to the (triclinic) Fairfieldite Group.

Varieties:

None

Synonyms:

Roselith

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals are elongated along [100], showing {011}, {111}, {010}, {110}, to 1.3 cm; commonly in spherical aggregates and druses.

Twinning:

Very common on {100} with {100} as composition plane, contact twins and fourlings.

Physical Properties

Cleavage:

Perfect on [010]

Fracture:

Spintery

Tenacity:

Brittle

Moh's Hardness:

3.5

Density:

3.46 - 3.74 (g/cm³); density increases with Co content

Luminescence:

Not Fluorescent

Radioactivity:

Not Radioactive

Other:

Readily soluble in acids.

Optical Properties

Color:

Pale rose-pink to dark rose-pink; rose-pink in transmitted light, may be color zoned. Darker coloured crystals frequently exhibit marked color zoning due to variations in composition.

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.725 - 1.735  Biaxial ( - )

Birefringence:

0.010

Dispersion:

Weak to Strong; r < v

Pleochroism:

Visible; X = pale rose-pink to dark rose-pink; Y = paler rose-pink; Z = palest rose-pink.

Occurances

Geological Setting:

A rare secondary mineral in cobalt-bearing hydrothermal mineral deposits.

Common Associations:

Talmessite (Bou Azzer, Morocco)

Common Impurities:

None

Type Locality:

Rappold Mine, Neustädtel, Schneeberg District, Erzgebirge, Saxony, Germany

Year Discovered:

1824

View mineral photos:

Roselite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Roselite is a very rare secondary mineral in cobalt-bearing hydrothermal mineral deposits. It is an extremely rare faceted gem. Gems are a beautiful pale rose-pink to dark rose-pink and always very small because crystals are small. One current source of crystals is Bou Azzer, Morocco.

Distribution: In Germany, from the Rappold and Daniel mines, Schneeberg, Saxony; at the Friedrich Christian mine, Wildschapbachtal, and the Anton mine, Heubachtal, near Schiltach, Black Forest. From Bou Azzer, Morocco. In the Talmessi mine, 35 km west of Anarak, Iran. From Huercal Overa, Almer´ia Province, and at Molvizar, Granada Province, Spain.
 

  
Roselite gems for sale: