Cheverie Rock Revelry EarthCache
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We came to this spot in search of a physical cache (GCWZDY) and we
were just amazed at this location. Unlike anywhere we have been,
the geology of this location is worth the trip. As well, it is a
spectacular spot for rockhounding along the beach here.
The area around Cheverie was active with mining and quarrying
operations in the late 1800's. Two manganese mines and a gypsum
quarry operated within this immediate area. A bit further inland
several more gypsum quarries operated, all now long abandoned.
This specific location takes you to a spectacular cliff and shore
of anhydrite and gypsum.
So what is anhydrite?
Anhydrite is a mineral - anhydrous calcium sulfate, CaSO4. It is in
the orthorhombic crystal system, with three directions of perfect
cleavage parallel to the three planes of symmetry. Distinctly
developed crystals are somewhat rare, the mineral usually
presenting the form of cleavage masses.The colour is white,
sometimes greyish, bluish or purple. On the best developed of the
three cleavages the lustre is pearly, on other surfaces it is
vitreous. When exposed to water, anhydrite readily transforms to
the more commonly occurring gypsum by the absorption of water.
Anhydrite is most frequently found in salt deposits with gypsum; it
was, for instance, first discovered, in 1794, in a salt mine near
Hall in Tirol. In this occurrence depth is critical since nearer
the surface anhydrite has been altered to gypsum by absorption of
circulating ground water.
From an aqueous solution calcium sulfate is deposited as crystals
of gypsum, but when the solution contains an excess of sodium or
potassium chloride anhydrite is deposited if temperature is above
40°C. This is one of the several methods by which the mineral has
been prepared artificially, and is identical with its mode of
origin in nature, the mineral is common in salt basins.
The name anhydrite was given by A. G. Werner in 1804, because of
the absence of water of crystallization, as contrasted with the
presence of water in gypsum. Some obsolete names for the species
are muriacite and karstenite; the former, an earlier name, being
given under the impression that the substance was a chloride
(muriate).
In order to claim this earthcache, you MUST do the following
tasks. Do NOT post a found log before receiving confirmation from
the cache owner. Failure to follow what is outlined will result in
deletion of the log.
1)Take a picture of yourself at the posted co-ordinates with
gps in hand. The sample picture should be a good example. Post this
picture once you have received comfirmation of your find from the
cache owner.
2)Find a sample of anhydrite OR gypsum and take a picture of
your gps with it. Post a picture and identify it with your found
log.
3)E-mail the cache owner the answer to this question. What
is the specific graivty of anhydrite and how does this compare to
the specific gravity of gypsum?
This cache should be available to do at all but the highest
tides, however it's best done during low tide. Be sure to check
tide times before you go!
Additional Hints
(Decrypt)
Yvfgra gb gur fanc, penpxyr cbc nf lbh jnyx ba gur ebpxf.
Treasures
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