Larvikite
Larvikites (after the town of Larvik in Norway ) are coarse-grained plutonites . The main component of the Larvikite is alkali feldspar . The term is no longer used in the context of modern petrographic nomenclature, although it is very common and continues to be used as a local name for these rocks in the Oslo Graben . In the QAPF diagram for plutonites, they stand between syenites and monzonites and show characteristics of both groups.
Rock description
The bluish shimmering larvikites are anorthoclase - syenites with about 10 percent mica , augite and hornblende . They shimmer blue because of the submicroscopic segregation lamellae typical of anorthoclase . This effect is known as pseudochromasia . There are also brownish, dark green and silver shimmering larvikites.
Biotite occurs as accompanying minerals, and olivine and magnetite in some larvikite deposits . These dark accompanying minerals are stored between the dominant feldspar crystals.
The striking shimmering effect comes very close to the feldspar mineral labradorite , which also shimmers. Therefore, it used to be confused with the anorthosites : "Dark blue shimmering anorthosites (with labradorite as plagioclase) [...] are often confused with the blue shimmering larvikites [...] The larvikites are a specialty. The very sodium-rich potassium feldspar , the so-called Anorthoclase , like the labradorite from the plagioclase series, shows an interesting blue shimmer. "
Applications
These natural stones are often used because of their interesting shimmering decoration. The incident light refracts in the feldspars and leads to shimmering effects of these rocks.
Typical applications for this group of rocks are wall cladding, table tops and other interior design objects. At times, the Larvikites played an exposed role as grave and monument rock.
Natural stone types
- Labrador Hell ( Blue Pearl )
- Labrador Dark ( Emerald Pearl )
Photo gallery
Memorial from Labrador Hell in Backaplan, Gothenburg, Sweden by Claes Hake for 63 young Swedes who died in a discotheque fire on October 30, 1998.
Carillon in Berlin in the Great Tiergarten from Labrador Hell
University Library in Oslo , below Dark Labrador and above Light Labrador
Bronze monument to Richard E. Byrd on a base made of polished dark labrador
literature
- IUGS : Igneous Rocks . A Classification and Glossary of Terms. Ed .: RW Le Maitre et al. Cambridge University Press, Cambridge 2004, ISBN 0-521-61948-3 .
- Raymond Perrier: Les roches ornementales . Edition pro roc, Ternay 2004, ISBN 2-9508992-6-9 .
Individual evidence
- ↑ RW LeMaitre & IUGS: Igneous Rocks 2004, p. 101
- ↑ Dietmar Reinsch: Natural stone studies. An introduction for civil engineers, architects, preservationists and stonemasons. P. 109, Enke, Stuttgart 1991, ISBN 3-432-99461-3
- ↑ Perrier: roches ornementales. P. 180
- ↑ Dietmar Reinsch, Geology, in: Steinmetzpraxis. The manual for daily work with natural stone, ed. v. Educational center for the stonemasonry and sculpture trade, p. 227, Ebner, Ulm 1995, 3rd edition, ISBN 3-87188-139-2
