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.
LEIFITE specimens:
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LEIFITE specimen lei-1
$ 45.00
Dims: 1.1 x 1.0 x 0.7" (2.8 x 2.5 x 1.8 cm)
Wt: 15.9 g w/ base
Mount Saint Hilaire, Quebec, Canada
This specimen consists almost entirely of Leifite by weight. It occurrs in the form of intergrown sprays of radiating, trigonal prisms with a hexagonal cross-section. Though all of the sprays present are broken and incomplete, there are still many intact crystals present (see the second image). Their maximum length is about 0.6" (1.5 cm), and all have good form. Their edges are moderately well-defined and though their prism faces are heavily striated, their basal termination faces are very smooth and possess a bright, vitreous luster. All are cloudy and translucent, though the top few millimeters of each crystal shows noticeable transparence. Bits of a dark mineral accompany the Leifite- I cannot identify it. There is little or no host rock present, and the piece is hot-glued onto an acrylic base.
no photo
lei-1 ($ 45.00)
Mount Saint Hilaire, Quebec, Canada
LEIFITE specimen lei-3
$ 95.00
Dims: 1.9 x 1.5 x 0.9" (4.7 x 3.7 x 2.4 cm)
Wt: 0.9 oz. (26 g)
Mount Saint Hilaire, Quebec, Canada
This small hand specimen consists almost entirely of Leifite, in both acicular, radiating and apparently bladed, nearly tabular form. The specimen is in very good condition, showing little in the way of fresh damage, and crystals in the radiating cluster reach nearly 1.8" (4.6 cm) in length. Their hexagonal form is only easy to study in the crust atop the acicular spray, where the tabular and small bladed crystals rest. All are colorless to milky-white and show a pearly to silky luster, and are translucent to transparent. There is no host rock, though some rusty-brown to black material (perhaps goethite?) rests with the smaller crystals atop the spray.
no photo
lei-3 ($ 95.00)
Mount Saint Hilaire, Quebec, Canada
LEIFITE specimen lei-2
$ 69.00
Dims: 3.6 x 1.9 x 1.9" (9.2 x 4.7 x 4.7 cm)
Wt: 5.3 oz. (149 g)
Mount Saint Hilaire, Quebec, Canada
Several small, radiating Leifite sprays rest on the aegirine/feldspar base of this cabinet specimen. These sprays are generally in good condition and contain crystals that reach 0.4" (1.0 cm) in length. Their aggregation makes their hexagonal form difficult to study. All have a white color and a silky luster, and are dimly translucent at best. The base on which they rest is made up of muscovite, cleavelandite and aegirine, all of which show good crystal form in areas. Most noticeable on the piece is a single, large aegirine crystal that makes up most of the base. It has dimensions of 3.6 x 0.9 x 0.9" (9.2 x 2.3 x 2.2 cm), is in very good condition, and shows very good monoclinic form for its size.
no photo
lei-2 ($ 69.00)
Mount Saint Hilaire, Quebec, Canada
LEIFITE specimen lei-4
$ 85.00
Dims: 1.3 x 1.0 x 1.0" (3.4 x 2.6 x 2.5 cm)
Wt: 0.6 oz. (17 g)
Mount Saint Hilaire, Quebec, Canada
A single, radiating spray of tightly arranged acicular Leifites comprises this large thumbnail piece. These spiky crystals are generally in good condiiton, showing little damage, and reach lengths of nearly 1.5" (3.8 cm). All have reasonably good hexagonal form, though their acicular, radiaing habit makes this a bit difficult to discern. All have a milky-white color and show a silky luster, though a dark brown/black material gives some discoloration. There is no host rock, so the spray is affixed directly to the acrylic base.
no photo
lei-4 ($ 85.00)
Mount Saint Hilaire, Quebec, Canada
 

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