We spent a few days in the city of Paphos, and during that time we wanted to discover as many attractions in the area as possible. This is how we came to the Avakas Gorge. As soon as we left the parking lot, I spotted this excavation and my geologist self immediately hit on it.
The word gypsum comes from the Greek γύψος ("gypsos") through the Latin gypsus, and the Greeks adopted it from the Semitic language environment. Other names of ancient origin for gypsum: selenite (moonstone), alabaster and lapis specularis (mirror stone).
Physical and chemical properties
Chemical name: calcium sulfate
Formula: CaSO4 x 2 H2O
Crystal system: monoclinic
Mineralogical classification: Sulfates and related compounds (class); Hydrous sulfates without potassium anion (subclass)
Hardness: 1.5 - 2
Density: 2.32 g/cm3
Melting point: 1460 °C
Cleavage: excellent along one crystal plane, good along the other two.
Solubility: in hot hydrochloric acid.
His formation
Gypsum is primarily a rock-forming mineral as a salt material separated from seawater. It is the first product that precipitates from condensing seawater. It separates from seawater colder than 25 °C and less concentrated seawater. It forms secondarily wherever sulphide minerals are oxidized and calcium is also present in the environment. It is one of the most common minerals in the oxidation process in ore deposits.
Even in large quantities, it is practically chemically produced during the reduction of the sulfur dioxide content of flue gases using wet limestone technology, which on an industrial scale is so-called are carried out using desulfurization equipment.
Appearence
Its crystals are mostly tabular according to the (010) sheet, prismatic according to (110) or (111), or possibly needle-shaped. Its shape mostly depends on the conditions of its origin. In ore veins, it is more prismatic along the c axis; in clays it is isometrically lens-shaped or somewhat tabular according to (010) and forms crystal groups.
It is often twinned, mostly forming dovetail twins according to (100). Its granular-crystalline mass version is alabaster, fine fibrous gypsum is called selenite or satinspar.
The process of evaporation
Release of material by evaporation or vaporization. (Salt precipitation from seawater.) When a bay or lagoon of the sea closes off from open water, salt precipitation starts in it. The reason for this is that the water temperature and (in the absence of water supply) the salinity will increase over time. Gypsum is the first to separate, then - as the temperature and salinity of the water increases - this is followed by anhydrite, rock salt, and finally potash salts. This is how thick salt rock colonies are formed. In this, the appearance of the minerals is not their own shape, but fills the available space. The so-called gypsum roses are typical in desert areas. If you have been to a beach where the surface of the horizontally layered rocks is the tidal zone, the small and large depressions there can be covered by a thin, white crust of salt.
Oxidation of sulphide ore veins
If sulphide minerals with a high sulfur content are present in the near-surface mineralization, secondary gypsum formation takes place in contact with seepage waters (or even air humidity). In terms of their appearance, the minerals formed in this way are mostly needles or small plates. Their size is a few centimeters at most.
Usage
Its fine-grained, translucent version, alabaster, is used to make decorative objects and sculptures, while massive gypsum rock is used as burnt plaster.
Among construction industry products, it is used as a raw material for, for example, gypsum stucco (decoration), plasterboard (mounted partition walls, fire protection coverings, elements of some false ceilings, dry floors).
To log the Earthcache
To log this cache, send me a message through my geocaching profile either by clicking my name at the top of this cache page!
Go to the given coordinates!
1. Look carefully at the rock wall! Describe how you see the appearance of rock wall here! (Color, surface, fabric, etc.)
2. Do you think the gypsum here is of primary or secondary formation? Justify your answer!
3. Post a photo of you or your personal item!
Please do not give away any of the required information on either your logs or photos.
ANY ARMCHAIR LOGS WILL BE DELETED. TO LOG THIS GEOCACHE YOU MUST VISIT IT.
