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Dolomite crystals occur nearly as commonly as calcite crystals in Lockport dolomite rock.
The crystals are unusual in that the crystal faces are curved
as opposed to being flat as in most crystals. The composition is calcium magnesium
carbonate and like calcite they dissolve in dilute acids giving off
carbon dioxide in the process. They readily effervess in warm dilute hydrochloric
acid.
In the Lockport area, they are usually pinkish to white.
As one would expect from the name, dolomite is the major rock forming mineral in Lockport
dolomite rock.
Fluorite is a relatively rare find in the Lockport area.
However, in Dundas Ontario,
in the same formation of Lockport Dolomite, it is more common.
Chemically, it is calcium fluoride, and takes the form of usually purple
cubic crystals in
Lockport dolomite. Fluorite cleaves into very nice octahedrons, but the specimens
found in Lockport are rare and small and thus do not lend themselves to being
cleaved.
Crystals dissolve in sulphuric acid giving off
hydrogen fluoride, an acid that can etch glass and an acid to stay away from. It causes
ulcers on the skin that don't heal and require immediate medical attention.
Celestite
is another relatively rare mineral in the Lockport area but does occur in Lockport
dolomite in Dundas, Ontario (just south of Hamilton).
Chemically it is strontium sulphate and grades into barite with barium
replacing the chemically similar
strontium until one has the mineral barite (barium sulphate). Celestite is
considered the main ore for strontium.
Strontium gives a bright red in the flame test and strontium compounds are
used in fire works
displays for red. Celestite, when pure comes as clear crystals which are white to
redish in color.
Celestite is much sought after by collectors and museums
Celestite is often found where galena, sphalerite, and other
sulfides are found.
It is ranked 3 to 3-1/2 on the "hardness scale."
Celestite sometimes fluoresces under ultraviolet light. Not normally soluble in acids, is is slightly soluble in water.
A test for it is to insert into a flame and water the color of the flame (as detailed in previous commentary).
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