| Abstract: | In this area in N Idaho, three large and numerous small lenses of layered to massive anorthosite consisting of two, and locally three, types of plagioclase with minor hornblende and mica occur in aluminium silicate-rich garnet mica schist. In most of this anorthosite, megacrysts of andesine with bytownite inclusions are embedded in a fine-grained groundmass of bytownite or anorthite; locally, labradorite occurs rather than andesine. Some labradorite laths show Carlsbad twinning and rims of andesine around anorthite inclusions. Along the contacts, lenses of fine-grained bytownite anorthosite with some hornblende or garnet and quartz are common. These lenses could represent calcic parent rocks converted to two-plagioclase rocks by partial replacement of bytownite by andesine. -R.A.H. |
| Genre: | Article |
| ProdID: | 70014501 |
| Citation Author: | Hietanen, A. |
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| Citation End Page: | 79 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geological Society of Finland, Bulletin |
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| Citation Number Of Pages: | 9 |
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| Citation Search Results Text: | Role of replacement in the genesis of anorthosite in the Boehls Butte area, Idaho.; 1986; Article; Journal; Geological Society of Finland, Bulletin; Hietanen, A. |
| Citation Start Page: | 71 |
| Citation Volume: | 58 |
| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | Role of replacement in the genesis of anorthosite in the Boehls Butte area, Idaho.; 1986; Article; Journal; Geological Society of Finland, Bulletin; Hietanen, A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1986 00:00 -0600 |
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