31. It occurs in hornfels and siliceous marble xenoliths within and adjacent to a nepheline syenite intrusion. 32. In places the nepheline syenite assumes the form of a dark rock with large rounded white spots. 33. During the alkali syenite crystallization, the carbonate portion of silicate magma was separated forming carbonatitic magma. 34. Lujavrite is a rare variety of nepheline syenite having amphibole, aegirine pyroxene, nepheline and feldspar. 35. Biotite is rare, because in a syenite magma the formation of feldspar consumes nearly all the aluminium. 36. The segregation of the silica from the melt leaves it in a state that may favour syenite formation. 37. Close associations between syenite and monzogranites are common, particularly in post-orogenic extensional / transtensional settings. 38. This mineral occurs as an anchimonomineral veinlet that cross-cuts poikilitic nepheline syenite ( Hawthorne 2012 ). 39. Some of these terrestrial rocks are carbonatite, kimberlite, alkaline syenite , some rocks of sills and anorthosite. 40. The tomb is a syenite stone from the Vitosha mountains where Vazov loved to walk . ( ) ]]
