Minerals of Scotland

BREWSTERITE
& HARMOTOME

Classic zeolite minerals from Strontian.

STRONTIAN

Classic Minerals of Strontian

Brewsterite & Harmotome

Strontian Links

BREWSTERITE
(chemical formula - (Sr,Ba)2[Al4Si12O32].10H2O).

Strontian is the type locality for brewsterite.
It is also the premier occurence in the world for this strontium-bearing zeolite mineral and examples
from Strontian make for good specimens. Described as a new mineral from Strontian in 1822,
brewsterite has a restricted number of recorded occurences worldwide.

At Strontian, it is found in cavities as druses of sparkling greyish, creamy or whitish, elongated, hexagonal,
prismatic crystals. The crystals are commonly twinned and attain a size of several millimetres.

Brewsterite is encountered as rich crystal coatings or druses, on its own or, most commonly,
in association with galena, calcite and harmotome. More recently, it has been found occuring as small crystals in association with brown calcite at the Clashgorm Mine.

BREWSTERITE - Whitesmith Mine, Strontian, Argyll.
Small transparent crystals encrusting a scalenohedral calcite crystal.

BREWSTERITE - Whitesmith Mine, Strontian, Argyll.
Lustrous, honey-toned crystal druse. Crystals to 3mms.

BREWSTERITE - Whitesmith Mine, Strontian, Argyll.
Multiple-twins to 3mms.

BREWSTERITE - Whitesmith Mine, Strontian, Argyll.
Specimen with crystals covering matrix..

BREWSTERITE - Whitesmith Mine, Strontian, Argyll.
Multiple-twinned prisms to 3mms.

HARMOTOME
chemical formula - (Ba 0.5,Ca 0.5,K,Na)5[Al4Si11O32].12H2O.

Strontian is one of the premier sites in the world for harmotome, a barium-bearing zeolite mineral.

The species has been found at a number of other Scottish localities and there are several occurences in the rest of the UK also. However, none make for such fine specimens
as the examples from Strontian.

Beautiful druses of white, blocky crystals to 2 centimetres have been found. Normally, they are much smaller,
but, regardless of size, they still make for superb examples of this mineral.

Single crystals as well as complex and cross-twins
occur at the locality's mines. Harmotome is commonly associated with calcite, barite and brewsterite
and generally occurs as well-formed crystals.

Harmotome crystals may also contain inclusions of pyrite micro-crystals. This is particularly noticeable
in the smaller crystals.
(For an example, see minerals of strontian - other minerals).

HARMOTOME - Corrantee Mine, Strontian, Argyll.
A lustrous crystal to 1cm resting on calcite.

HARMOTOME - Whitesmith Mine, Strontian, Argyll.
Crystals to 12mms; (spec - 95 x 65 mms).

HARMOTOME - Corrantee Mine, Strontian, Argyll.
A bi-pyramidal crystal to 6mms and smaller associated crystals
with brewsterite on calcite.