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Llanite
Overview
Llanite is a hypabyssally intruded rhyolite
with phenocryst
s of microcline
and euhedral quartz
. The quartz crystals are blue hexagonal bipyramid
s. The unusual blue coloration of the quartz is thought to be due to ilmenite
inclusions . It is named after Llano County, Texas
, the only place where it is found (according to locals, however geologists have identified other locations this rock may be found according to Dr.
Rhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
with phenocryst
Phenocryst
thumb|right|300px|[[Granite]]s often have large [[feldspar|feldspatic]] phenocrysts. This granite, from the [[Switzerland|Swiss]] side of the [[Mont Blanc]] massif, has large white [[plagioclase]] phenocrysts, [[triclinic]] [[mineral]]s that give [[trapezium|trapezoid]] shapes when cut through)...
s of microcline
Microcline
Microcline is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase; it is more stable at lower temperatures...
and euhedral quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
. The quartz crystals are blue hexagonal bipyramid
Bipyramid
An n-gonal bipyramid or dipyramid is a polyhedron formed by joining an n-gonal pyramid and its mirror image base-to-base.The referenced n-gon in the name of the bipyramids is not an external face but an internal one, existing on the primary symmetry plane which connects the two pyramid halves.The...
s. The unusual blue coloration of the quartz is thought to be due to ilmenite
Ilmenite
Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....
inclusions . It is named after Llano County, Texas
Llano County, Texas
Llano County is a county located on the Edwards Plateau in the U.S. state of Texas. In 2010, its population was 19, 301. Its county seat is Llano, and the county is named for the Llano River....
, the only place where it is found (according to locals, however geologists have identified other locations this rock may be found according to Dr.
Unanswered Questions