GYPSUM
What is gypsum?
Pure gypsum is a white rock but sometimes impurities colour it grey, brown or pink. Its scientific name is calcium sulphate dihydrate and its chemical formula is CaSO42H2O. This means that, for every molecule of gypsum, there are two molecules of water. This is a most important fact in the gypsum story. If a piece of gypsum is ground to powder and heated, it will lose about three quarters of its water. When this powder is mixed with water the resulting paste sets hard as the water recombines to the original composition of the rock and so forms gypsum again. So this is very useful in the construction industry.
Common Uses:
- Construction: It is widely used as plaster of Paris and plasterboard (drywall). As plaster is used for creating decorative finishes on walls and ceilings, while gypsum board is used for interior wall and ceiling construction.
- Agriculture: Gypsum is applied to soil in agriculture to improve its structure and reduce soil compaction. It provides essential calcium and sulfur nutrients to plants and can help in reclaiming saline or sodic soils.
- Industrial Applications: Gypsum has various industrial uses, including in the production of cement, as a filler in paper and textiles, and as a component in making molds and casts.
- Art and Sculpture: Gypsum has a long history of use in art and sculpture. Artists use it to create intricate sculptures and molds for casting. Alabaster is a mineral composed of gypsum and various impurities, is much softer and easier to work than marble and a good material for mass production, though not suitable for outdoors use. Nottingham alabaster is a term used to refer to the English sculpture industry, mostly of relatively small religious carvings, which flourished from the fourteenth century until the early sixteenth century. Alabaster carvers were at work in London, York and Burton-On-Trent and many probably worked very close to the rural mines, but the largest concentration was around Nottingham. This has led to all the English medieval output being referred to as "Nottingham alabaster"..
Current gypsum extraction
Gypsum extraction in the UK takes place at five mines and one quarry. The open-cast quarry at Kilvington, near Newark on Trent, is the smallest operation. This extracts a high-quality gypsum used for speciality products. Two of the mines are 'far-flung': one at Kirkby Thore, Cumbria, and the other near Robertsbridge, East Sussex. The remaining three are in the midlands: Fauld (to the west of Tutbury, Staffordshire – uniquely this mine supplies the cement industry), East Leake, Nottinghamshire, and Barrow on Soar, Leicestershire (both with plaster and plasterboard manufacturing on the same sites).
The East Leake and Barrow on Soar mines exploit a once-continuous deposit of gypsum about 3.5 metres deep straddling the Leicestershire-Nottinghamshire boundary. However a significant geological fault running to the south of the county boundary means that the northern deposits are 80 metres deeper than the southern ones. The locations of the mine entrances were selected to allow 'drift' mining; access to the working faces is achieved down slopes of about 1:50 gradient.
TASKS
Please submit your answers before logging a find, as deletion of finds where answers have not been submitted may cause upset.
At the listed coordinates you will find a rock.
Message or email me with answers to the following:
1. Describe the rock (colour, approx size in feet or metres, texture)
2. Is it below 2 on the mohs scale of hardness? If it is Gypsum it has a hardness below 2 on the Mohs scale and scratching it with your fingernails will result in you being able to scrape small particles off the rock. (See image in gallery for mohs scale)
3. Take a photo of yourself or a personal item at GZ. Attach the photo to your log.