Morphology
Vorma (1976) states that rapakivi granites can be defined as:
- Orthoclase crystals have rounded shape
- Most (but not all) orthoclase crystals have plagioclase rims (type Vyborgite, named after the city of Vyborg)
- Orthoclase and quartz have crystallized in two phases, early quartz is in tear-drop shaped crystals (type Pyterlite, named after the location of Pyterlahti).
Latter definition by Haapala & Rämö states:
Rapakivi granites are type-A granites, where at least in larger associated batholites have granites with rapakivi structures.
Read more about this topic: Rapakivi Granite
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