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Leifite
Leifite is a rare tectosilicate. Tectosilicates are built on a framework of tetrahedra with silicon or aluminium at the centre and oxygen at the vertices; they include feldspars and zeolites, but leifite does not belong in either of these categories. It is a member of the leifite group, which includes telyushenkoite (Cs,Na,K)Na6(Be2Al3Si15O39) and eirikite KNa6Be2(Si15Al3)O39F2.〔 Leifite was discovered in 1915, and named after Leif Ericson who was a Norse explorer who lived around 1000 AD, and was probably the first European to land in North America, nearly 500 years before Christopher Columbus.〔 Eirikite was named in 2007 after Eirik Raude, or Erik the Red, (950–1003), who discovered Greenland and who was the father of Leif Ericson. The third mineral in the group, telyushenkoite, was discovered in 2001. It was not named after any of Leif Ericson's family members, but after a professor of geology in Turkmenistan.
== Structure ==
Leifite is a trigonal mineral, class 2/m, space group Pm1.〔Canadian Mineralogist (2002)40:183-192〕 There are 3 formula units in the unit cell (Z = 3), and cell dimensions are 14.4 Å in the a direction and 4.9 Å in the c direction.〔American Mineralogist (1972) 57:1006〕〔Bulletin of the Geological Society of Denmark 20:134 (1970)〕 It contains OH groups, but no water of crystallization as was previously assumed.〔Norsk Geologisk Tidsskrift (1995) 75:243-246〕
Tetrahedrons of silicon or aluminium atoms surrounded by four oxygen atoms link to form six-membered rings stacked along the c direction to form channels, similar to those in zeolites.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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