Diaspore is found as a hydrothermal mineral in some alkalic syenite pegmatites, such as this one from Saga Quarry, Sagåsen in Norway. Note the subtle lilac colour in some crystals of diaspore in PPL. Here it is associated with natrolite.
Rotation 1 - diaspore AlO(OH)
Rotation 2 - natrolite Na2(Si3Al2)O10•2H2O
Many thanks to Alessandro Da Mommio for providing us with this sample. Alex describes this sample here.
The Ilimaussaq alkaline complex is the type locality for agpaitic nepheline syenites and represents an enormous concentration of rare elements, notably Li, Be, Nb, Zr, REE, Y, Th and U. Around 220 mineral species have been identified. We can't identify all the minerals present in these samples. Email us at email@example.com if you can help.
Note we have recently expanded the collection to include other syenite complexes worldwide.
See also Alex Strekeisen's great website for more information on syenite complexes.