A drill core sample from Mount Poachvumchorr, Khibiny, the rock is fine grained rischorrite. What you see is white potassium 
feldspar and gray foid minerals. Because rischorrites are relatively rich in potassium compared to the rest of Khibiny, the foid mineral
is not only nepheline, but also contains small amounts of Kalsilite. Both Nepheline and Kalsilite look identical.
This core is  from a depth of 400 meters. At this depth there is a 15 meter thick rischorrite body at Poachvumchorr.
[photo/collection: Maurice de Graaf. Pavel Kartashev for additional info]