#geololgy

[bijoux-et-mineraux]

Fluorite with Quartz - Guxian, Henan Province, China

[underthescopemineral]

Stolzite              

Pb(WO4)

Locality:

Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany

Field of View: 0.36 mm

A member of stolzite-wulfenite series.

Photo: Michael Förch

Stolzite is a rare secondary mineral in the oxidized zones of hydrothermal tungsten-bearing lead deposits. May be bright red to red-orange (LW UV), and lemon-yellow (SW UV). Melting Point 1123° C. Decomposed by HCl with the separation of yellow tungstic acid.

[underthescopemineral]

Pyrolusite

Mn4+O2

Locality:

Herdade dos Pendões Mine, São Luís, Odemira, Beja District, Portugal

Field of View: 2.8 mm

Group of pyrolusite ‘blades’ on cryptomelane.

Pedro Alves’ Photo

Pyrolusite is a mineral consisting essentially of manganese dioxide and is important as an ore of manganese. Its name is from the Greek for fire and to wash, in reference to its use as a way to remove tints from glass. Formed under highly oxidizing conditions in manganese-bearing hydrothermal deposits and rocks; in bogs and lakes, under shallow marine conditions; commonly an alteration product of manganite. Pyrolusite is extensively used for the manufacture of spiegeleisen and ferromanganese and of various alloys such as manganese-bronze. As an oxidizing agent it is used in the preparation of chlorine;          

[underthescopemineral]

Conichalcite

CaCuAsO4(OH)

Locality:

Km-3 Mine, Lavrion (Laurion; Laurium), Lavrion District Mines, Lavrion District (Laurion; Laurium), Attikí Prefecture (Attica; Attika), Greece

Field of View: 4 mm

Green transparent conichalcite. 

Collection and photo: Stephan Wolfsried.

Conichalcite is a relatively common arsenate mineral related to duftite. It is green, often botryoidal, and occurs in the oxidation zone of some metal deposits. Conichalcite forms in the oxidation zones of copper orebodies. Here groundwater enriched with oxygen react with copper sulfide and copper oxide to produce an array of minerals such as malachite, azurite and linarite.