Lazurite
(Lapis Lazuli)
is one of
the members of the Feldspathoid
group of minerals that includes Cancrinite,
Haüyne,
Lazurite, Leucite,
Nepheline and Sodalite. Minerals with chemistries that are close to
those of the alkalai Feldspars, but are poor in silica
(SiO2)
content, are called Feldspathoids. Lazurite is also
a member of the Sodalite group of minerals that includes Hackmanite,
Haüyne
and Tugtupite.
Lazurite could be considered a Sulphur rich form of
Haüyne. Lazurite crystals are rarely found however.
It is more commonly found combined with other minerals
as a rock called Lapis Lazuli, or just Lapis. Lazurite
and Lapis are two separate things; Lazurite is a mineral
and Lapis Lazuli is a rock composed of many different
minerals; but we are grouping them together on
this page since they are so closely related. Lapis contains
mostly massive forms of Lazurite combined with Haüyne,
Sodalite, Nosean, (all members of the Sodalite group
of minerals) and white Calcite,
Pyrite, and other minerals. The Calcite and Pyrite give
Lapis a very attractive look and the presence of Pyrite
distinguises Lapis from its blue cousin - Sodalite rock,
which lacks Pyrite.
The
name Lazurite is often confused with another blue mineral,
the phosphate mineral Lazulite.
Although the names are similar, their crystal habit
is very different. Lazurite is very rarely found as
distinct crystals and Luzulite has good crystal habit
and vitreous luster. The carbonate
mineral Azurite has
a very similar color to Lazurite but is associated with the green carbonate
mineral Malachite
and reacts to acids.
Lapis
Lazuli has been mined for centuries from a source still
in use today in the remote mountain valley of Kokcha,
Afghanistan. Although there are other sources of Lapis
worldwide, Afghanistan still produces the finest quality
material.
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