General

The materials used from Portsdown Hill are the flints and chalk

Chalk

• Agricultural lime
• Industrial lime (cement, mortar etc)
• Carpenter's chalk - but not school master's chalk!
  (Blackboard chalk is not only not 'chalk'. it is not a limestone at all. Blackboard chalk is a form of Plaster of Paris, which is made of gypsum, which is a sulphate of calcium.
  Where limestone chalk is CaCO₃, the gypsum of blackboard chalk is CaSO₄.2H₂O)
• ...
• Aquifer for water - and sometimes an oil reservoir or seal
• Secret caves to hide smuggled goods
• Serendipitously for the inhabitants of Portsmouth, as a protective lining of the Victorian lead water pipes - precipitations of calcite lined the pipes, so preventing lead dissolving into the drinking water. This saved the local populace from the maddening effects of lead poisoning, that affected some in other areas.

Flint

• Prehistoric tools and weapons
• Military muskets and tinder boxes
• Hard outer layer of buildings

For any comments, suggestions or contributions, please e-mail me at: portsdown@bbm.me.uk