1) Trigonal mineral 
Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world. It was discovered in platy sheed{clarify|date=May 2013|reason=Not in any dictionary I have access to} form of 1mm hexagonal crystals. It was first described in 1977 by...