FREE: Section of Chiastolite crystal with cross pattern

The listing, Section of Chiastolite crystal with cross pattern has ended.

Section of Chiastolite crystal with cross pattern

Chiastolite is a variety of the mineral andalusite with the chemical composition Al2SiO5. The variety chiastolite commonly contains dark inclusions of carbon or clay which form a cruciform pattern when shown in cross-section.
There are several theories regarding the formation of the chiastolite cross, however the most widely accepted theory, proposed by Frondel in 1934, suggests
that there is a selective attachment of impurities at the rapidly growing corners of andalusite crystals. As the concentration of these impurities
(which consist primarily of graphite) increases, the growth of the crystal is slowed. This concentrated impurity deposit forms a re-entrant as it is absorbed
by the growth of the andalusite porphyroblast. The cycle of growth-retardation-growth then repeats itself, creating a featherlike pattern of graphite along four radiating
'arms'.
Small - medicine pouch size or for collection.


*Random Cat Photo - Gadget by Elias Saba.