Kahlenbergite

kahlenbergite

pseudobrookite

gehlenite

dorrite

Images

Formula: KAl11O17
Oxide, epitaxially replaced and overgrown by hibonite
Crystal System: Hexagonal
Specific gravity: 3.40 calculated
Hardness: 6 to 7
Streak: Light brown
Colour: Light brown, yellow-brown, light orange
Environments

Metamorphic environments

Kahlenbergite is a new mineral, approved in 2019.

Localities

At the type locality, the Kahlenbergite occurrence, Har Parsa, Hatrurim Basin, Tamar Regional Council, Southern District, Israel, kahlenbergite occurs in pyrometamorphic rocks as platy, light brown crystals, epitaxially replaced and overgrown by hibonite. Associated minerals include wollastonite, spinel, pseudobrookite, hematite, gehlenite, dorrite and corundum (Mindat).
Kahlenbergite is found in small hematite segregations enriched by hibonite within wollastonitegehlenite hornfels. It is a high-temperature mineral that occurs together with hibonite, corundum, hematite, dorrite and other anhydrous minerals. Kahlenbergite and associated minerals crystallise at temperatures of not less than 1000oC under strongly oxidising conditions.
This is the largest occurrence of pyrometamorphic rocks in the Dead Sea rift area. Occasionally, the hornfels shows a vesicular texture, which is an indicator for partial melting. The main minerals of the hornfels are wollastonite, gehlenite, esseneite-diopside, andradite and anorthite. Sometimes, minerals of the levantitelatiumite series and celsian appear in substantial amounts. Minerals of the spinelmagnesioferrite series, hematite, baryte and silicon-bearing apatite are accessory minerals. Vesicular spaces are filled with zeolites, calcium hydrosilicates, and occasionally calcite and ettringite. Moreover, spinel, corundum and pseudobrookite are present in association with kahlenbergite. Dorrite was detected at the boundary of the hematite segregation with hornfels. The new mineral gorerite is observed in spinel exsolutions (EJM 33.4.341-355).

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