Logging Tasks:
In the road outcrop, you find almost exclusively alabaster on both sides. Describe the characteristics of the alabaster in the road outcrop. Describe in two or three sentences what you see in the outcrop:
1) What colors are visible?
2) Is the alabaster coarse- or fine-grained?
3) Is the alabaster layered, or does it occur irregularly in the outcrop?
4) What other rock commonly used in buildings resembles the alabaster in this outcrop?
5) How would you be able to distinguish these materials without special tools?
In front of the road cut, on the northern side, there is a slope covered with selenite. Describe the properties of selenite. Describe in one or two sentences what you see in the outcrop:
6) What shape are the crystals?
7) Are they transparent or opaque?
8) Are they sorted, or do the crystals lie irregularly on the slope?
Weathering processes. Describe in one or two sentences what you see in the outcrop:
9) Can you find signs of weathering in the road cut (cracks or fissures)?
10) Are there signs of precipitation of dissolved material on the walls of the cut?
4. A photo of you at the GZ showing you or a personal item with your cacher name, with the road cut in the background. It would be nice to have an additional photo from WP2 in your log (not mandatory).
View from the parking lot toward the street intersection (GZ). On the right side of the image, you can see the slope with the selenite.
Gypsum – Alabaster – Selenite and a crisis
During the latest Miocene (Messinian), about 5-6 million years ago, the Mediterranean Sea became isolated from the Atlantic Ocean and was in the grips of a salinity crisis. As evaporation took place, waters turnes hypersaline and extensive deposits of evaporite minerals formed. In Cyprus, the Messinian salinity crisis is recorded in the Kalavasos Formation, which comprises gypsum alternating with marly chalk, chalky marl and minor silt. These evaporites are likely to have formed in small and somewhat isolated basins, in which the maximum brine depth was probably less than 100 m. Very coarse-grain gypsum crystallized in shallow water (no deeper than 10m) at the basin edge or within shallow lagoons.
Gypsum is a soft sulfate mineral. Gypsum is the most common sulfate mineral. Pure gypsum is white, but other substances found as impurities may give a wide range of colors to local deposits. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite.
Example of what alabaster looks like
All varieties of gypsum, including selenite, satin spar, and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO4·2H2O. Selenite contains no selenium; the similar names both derive from Greek selḗnē (σελήνη 'Moon'). It is a particularly high-purity form of gypsum. The large, transparent crystals can easily split into thin sheets. In Roman times, selenite was an expensive luxury item because of its rarity. They used the transparency of selenite for window panes. Some large crystals are shaped like a swallowtail. At the GZ (or in the surrounding area), if you're lucky you migth see crystals up to 15 cm long. If you head north from the GZ along the road and then take the gravel road (from here N34° 48.812 E032° 34.031) toward the small church (N34° 48.971 E032° 34.099), after a few meters you’ll notice that you’re walking on a "glass" (selenite) path.
A very fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various sorts (like marble). Marble (most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2)) and alabaster are readily distinguished by their different hardness: gypsum alabaster (Mohs hardness 1.5 to 2) is so soft that a fingernail scratches it, while marble (Mohs hardness 3) cannot be scratched in this way but yields to a knife.
Example of what selenite looks like
Safety and Rules of Conduct.
At the outcrop, please only look and touch! Please do not collect any rocks or minerals. The hardness test using your fingernail should be performed on material that has fallen from the wall in sufficient quantities and is lying on the ground. Please be aware that rocks may fall from the wall at any time due to erosion. The road where the outcrop is located is narrow, and vehicles occasionally pass through this section of the road.
What can you discover here?
That the same material can take on different forms, and that different materials can look alike. You can learn to distinguish between these materials and draw conclusions about how they were formed. You can discover that, even though you are 400 meters above sea level, you are examining the former seafloor.
Waypoint 2 (optional)
There is a traditional cache at the GZ, and there is also one at the optional waypoint 2. If you visit waypoint 2, you can see some very beautiful outcrops and a deep shaft with wonderful layering.
Gypsum dissolves in rainwater and groundwater and then recrystallizes as soon as it comes into contact with oxygen in the air.
Waypoint 2: Karst formation: a deep shaft formed by water
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