THE MINERAL LEIFITE

Chemistry: Na6Be2Al2Si16O39(OH)2 - 1.5H2O; Hydrated Sodium Beryllium Aluminum Silicate Hydroxide Fluoride.
Class: Silicates
Subclass: Tectosilicates
Uses: Only as a mineral specimen.
Specimens

Leifite is a rather rare and obscure beryllium silicate mineral. It forms in rare rocks known as agpaites which are igneous rocks of unusual concentrations. They are characterized by high concentrations of alkali metals especially sodium and low concentrations of silicon and aluminum. They are feldspar and feldspathoid rich and being low in silicon, contain little or no quartz. Agpaite pegmatites contain unusual minerals because they originate with unusual elements. Elements such as beryllium, zirconium, titanium, niobium, barium, strontium, thorium and rare earth metals are all found in the compositional mix that represents this rock type.

There exists agpaite in several places around the world, but by far the most famous are the ones at the Kola Peninsula in Russia, Narsarsuk, Greenland and the one above all the rest, the mines of Mount Saint Hilaire, Quebec. Leifite is one of the rare minerals that can form in these silica starved, unique chemical environments. Other minerals coming from these unique localities include catapleiite, synchysite, serandite, elpidite, aegirine arfvedsonite, eudialyte and analcime to name a few.

PHYSICAL CHARACTERISTICS:

Color is white or colorless.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System is trigonal.
Crystal Habits include prismatic to acicular crystals with a hexagonal cross-section and a basal termination. Crystals are striated lengthwise. Aggregates are clustered into radial sprays.
Hardness is 6.
Specific Gravity is 2.6
Streak is white.
Associated Minerals are calcite, aegirine and other rare minerals.
Notable Occurrences include Narsarsuk, Greenland and Mount Saint Hilaire, Quebec.
Best Field Indicators are crystal habit, locality and hardness.