This EC can be done at the same time or separate to the other EC we have in the same location, we have just posted the coordinates across the road so they sow up a little better on the map. Click for GC6QQBP Belemnites here
Whilst in the area digging for Belemnites we kept coming across these little pieces of ‘glass’, they were prolific and in some case pretty when they caught the sun. After a little investigation I was able to tell Geo daughter that these pieces of ‘glass’ are in actual fact a type of gypsum (calcium sulphate - CaSO4), which is a rock despite being semi-transparent.
We decided it would be fun to teach other cachers about what we learnt.
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. A massive fine-grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, Byzantine empire and the Nottingham alabasters of medieval England. It is the definition of a hardness of 2 on the Mohs scale of mineral hardness. It forms as an evaporite mineral and as a hydration product of anhydrite.
Gypsum is moderately water-soluble (~2.0–2.5 g/l at 25 °C) and, in contrast to most other salts, it exhibits retrograde solubility, becoming less soluble at higher temperatures. When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, (bassanite, often simply called "plaster") and, if heated further, to anhydrous calcium sulfate (anhydrite). As for anhydrite, its solubility in saline solutions and in brines is also strongly dependent on NaCl concentration. Gypsum crystals are found to contain anion water and hydrogen bonding.
Gypsum in this geological region (termed the Eromanga Basin) is derived from two sources. Much, but not all, of it was formed in the ancient shallow seas 100 million years ago, when under conditions of high evaporation and low water circulation the combination of calcium (Ca) and sulfate (SO4) formed a relatively insoluble mineral on the sea bed. However some of the gypsum is of much more recent origin - sulfide (SO3) and sulfur (S) from the weathering Cretaceous shales (where it was formed from the decomposition of marine organisms) being oxidised to into sulfate (SO4) and combining with the ubiquitous lime (Ca) also produces the mineral.
To log this Earth Cache we require you to find some Gypsum, consider the information given and perhaps if you need to do some research of your own, then message us with the following answers to the best of your ability;
1. How big is the piece you have found, what characteristics make you think it is Gypsum?
2. We would like you to do a little experiment, please be responsible and DO NOT DO THIS AT GZ, take a piece of Gypsum home with you (it’s ok we have cleared this with the local ranger), when you get home, familiarise yourself with this piece, note the colour texture and density. For the next part, children please ask an adult for some help. Hold a piece with some tongs on a naked flame for 20 seconds - a minute, what happens to it? Note the changes.
3. A photo of your team or GPS near GZ or while conducting he experiment (don't put any spoilers in your photo though), upload as many photos as you like! (Optional)
You are welcome to log your answers straight away to keep your TB's and Stats in order but please message us with your answers within 24 hours. Cachers who do not fulfil the Earth Cache requirement will have their logs deleted.
Source Wikipedia, Dr. Patrick Smith
