Kwartsiet: verschil tussen versies
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k r2.7.1) (Robot: toegevoegd: an:Quarcita |
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Regel 10:
'''''quartzite''' (1) A granoblastic metamorphic rock consisting mainly of quartz and formed by recrystallization of sandstone or chert by either regional or thermal metamorphism; metaquartzite. Cf: orthoquartzite.''
''(2) A very hard but unmetamorphosed sandstone, consisting chiefly of quartz grains that have been so completely and solidly cemented with secondary silica that the rock breaks across or through the grains rather than around them; an orthoquarizite. The cement may grow in optical and crystallographic continuity around each quartz grain, thereby tightly interlocking the grains as the original pore spaces are filled. Skolnick (1965) believed that most sedimentary quartzites are compacted sandstones developed by pressure solution of quartz grains. The term is also used for a metamorphic rock produced by recrystallization of a sandstone.'' en verderop:
'''''quartzitic sandstone''' A term used by Krynine (1940, p.51) for a sandstone that contains 100% quartz grains cemented with silica. The term is essentially equivalent to orthoquartzite. Cf: quartzose sandstone.''</ref> dit was in het engels maar nu in het nederlands
Omdat beide typen dezelfde chemische samenstelling en uiterlijke kenmerken hebben, is het zeer moeilijk deze op het oog te onderscheiden.
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