GYPSUM (from Italian Dictionary)
- Mineral, calcium sulphate dihydrate: CaSO4.2 (H2O)
- It is produced by the crushing and the baking of the mineral, and it is used for created shapes and casts of sculptures, models and others. Quick setting gypsum is used for modelling and walling works. For extension, the sculpture meld by gypsum. In some locutions it can be used like ‘’di gesso’’ in the sense of ‘’have a pale face’’ or a ‘’deathly pale’’, it can be used also in the phrase ‘’restar di gesso’’ in English ‘’to stand rooted to the spot’’ with the meaning of dazed. Gypsum is also used for design the object for write on the board; chalk.
- Commonly it is used with the meaning of plaster cast or plaster cast device.
- Hygrometic regulation: it is a natural regulator of temperature
- Thermal insulation: it is a good thermal insulator thanks to his porous structure
- Sound insulation: it has good features fono- attenuanti (sound-mitigating); it reduces the transmission of sounds, and fono- assorbenti (sound- absorbent); it limits the reverberation.
- Resistance to the fire: is a material non-combustible, so it can delay flames’ diffusion.
- Light reflection: it has an high coefficient of light radiation and is useful for illuminate the spaces.
- Hygiene and healthy: since the gypsum has a natural origin, it doesn’t issue dangerous substances, it protects from insects and parasites attacks.
Some crystals of ‘’gesso selenitico’’ (lapis specularis as known as mirror’s stone), particularly transparent and with a considerable dimension, split apart in a very thin layers, letting the light pass through it.
The Roman used it instead of glass to close the windows, or to created scenography effects during the public games, and so on. It was a precious and refined mineral, was trade throughout the entire empire, it was extract by the children because they were the only that can enter in the smallest cavity.
Plinio mentions the mineral in his ‘’Naturalis Historia’’ where he points out the most important caves in the Mediterranean basin, including Sicily.