Editing Feldspar (section)

==Structure==
The structure of a feldspar crystal is based on aluminosilicate tetrahedra. Each tetrahedron consists of an aluminium or silicon ion surrounded by four oxygen ions. Each oxygen ion, in turn, is shared by a neighbouring tetrahedron to form a three-dimensional network. The structure can be visualized as long chains of aluminosilicate tetrahedra, sometimes described as [[crankshaft]] chains because their shape is kinked. Each crankshaft chain links to neighbouring crankshaft chains to form a three-dimensional network of fused four-member rings. The structure is open enough for cations, typically sodium, potassium, or calcium, to fit into it and provide charge balance.{{sfn|Klein|Hurlbut|1993|pp=533-534}} 
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File:Anorthite crankshaft.png|Diagram showing part of a crankshaft chain of feldspar
File:Anorthite c.png|Feldspar crystal structure viewed along the c axis
File:Anorthite a.png|Feldspar crystal structure viewed along the a axis
File:Anorthite b.png|Feldspar crystal structure viewed along the b axis
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