| 11. | The distinctive texture of rapakivi granite is due to oligoclase rims on orthoclase phenocrysts.
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| 12. | The feldspar component of syenogranite is predominantly alkaline in character ( usually orthoclase ).
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| 13. | Some intergrowths of orthoclase and albite have an attractive pale moonstone when used in jewellery.
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| 14. | The feldspar is usually orthoclase, but can also be albite, oligoclase or microcline.
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| 15. | Associated minerals include : epidote, tremolite, glaucophane, orthoclase, quartz and calcite.
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| 16. | Other parts more rich in volatiles have formed pegmatites featuring milky quartz and pink orthoclase.
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| 17. | Associated minerals include bixbyite, quartz, orthoclase, topaz, spessartine, pseudobrookite and hematite.
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| 18. | Alkali feldspar dominates, commonly represented by orthoclase and the exsolved lamellar albite, form perthite.
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| 19. | Orthoclase is generally stable and unaffected.
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| 20. | Pini described a variety of orthoclase called Adularia from the Adula Alps near Gotthard in 1780.
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