Håleniusite- (La,Ce)OF is a yellow isometric

Cubic crystal system

In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....

 mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

. It has a dull, earthy lustre

Lustre (mineralogy)

Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....

. The geological setting of håleniusite-(La) is in vug

Vug

Vugs are small to medium-sized cavities inside rock that may be formed through a variety of processes. Most commonly cracks and fissures opened by tectonic activity are partially filled by quartz, calcite, and other secondary minerals. Open spaces within ancient collapse breccias are another...

s and leaching zones of massive ferriallanite-(Ce), intimately intergrown with cerite

Cerite

Cerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the Ce rich species and the La rich species...

-(Ce) and bastnäsite

Bastnasite

The mineral bastnäsite is one of a family of three carbonate-fluoride minerals, which includes bastnäsite- with a formula of CO3F, bastnäsite- with a formula of CO3F, and bastnäsite- with a formula of CO3F. Most bastnäsite is bastnäsite-, and cerium is by far the most common of the rare earths in...

-(La).

It was discovered in 1986 at Bastnäs mines, Riddarhyttan, Skinnskatteberg

Skinnskatteberg

Skinnskatteberg is a locality and the seat of Skinnskatteberg Municipality in Västmanland County, Sweden with 2,395 inhabitants in 2005.-External links:* - Official site...

, Västmanland

Västmanland

' is a historical Swedish province, or landskap, in middle Sweden. It borders Södermanland, Närke, Värmland, Dalarna and Uppland.The name comes from "West men", referring to the people west of Uppland, the core province of early Sweden.- Administration :...

, Sweden and named in honor of Ulf Hålenius, director of the mineralogy department at the Swedish Museum of Natural History

Swedish Museum of Natural History

The Swedish Museum of Natural History , in Stockholm, is one of two major museums of natural history in Sweden, the other one being located in Gothenburg....

 in Stockholm

Stockholm

Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...

, Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

.