Gypsum is a common sedimentary
mineral precipitated from sea water in shallow bays. Hardness is
from 1.5 to 2.0.
It has the same chemical composition
as the mineral Anhydrite, but contains water in its structure
whereas Anhydrite does not.
Gypsum commonly occurs as tabular
crystals, but about 70 crystal types are known. One type of crystal
is called "Desert Rose", which is rosette shaped Gypsum with sand
inclusions.
A massive, fine grained variety of
Gypsum called Alabaster is carved for ornamental use, such as
artistic sculptures and pottery.
The largest crystals ever found on
earth were of Gypsum. In the cave Chihuahua in Mexico there were
found crystals about 10 meters
long and 2 meters wide.
On the place of the beach where
coordinates will lead you you can see impressive gypsum cliffs
known as the Gypsolithoi. Here you can take a snapshot of you in
front of the rock and paste it into your log as an optional
condition of this earthcache.
Mandatory condition - email me via
profile:
1) The chemical formula of Gypsum
2) English or Latin names of four
chemical elements that are contained in the formula. You can add
names of these chemical elements in your native language if it is
different from english.
3) Approximate depth of the sea 3
meters from the cliff
4) Try to determine the hardness of
the mineral in the cliff (from 1 to 10). You can use your finger
nail and/or something else (On the Mohs scale, graphite (a
principal constituent of pencil "lead") has a hardness of 1.5; a
fingernail, 2.2–2.5; a copper penny, 3.2–3.5; a
pocketknife 5.1; a knife blade, 5.5; window glass plate, 5.5; and a
steel file, 6.5. A streak plate (unglazed porcelain) has a hardness
of 7.0. Using these ordinary materials of known hardness can be a
simple way to approximate the position of a mineral on the
scale.)
