1808

Calcium

• Calcium carbonate is part of Earth’s carbon cycle
• and calcium is essential for all living organisms.
• Use of lime, limestone, and lime plaster
• goes way back, before over seven thousand years BCE.
• Roast the carbon dioxide out of limestone or seashells
• to get quicklime, calcium oxide.
• Lime was considered to be an undecomposable element until
• Humphry Davy decomposed it into oxygen and a metal.

Atomic number 20

• Calcium carbonate for coral reefs.
• Calcite, aragonite, and vaterite.
• Limestone for the Rock of Gibraltar
• and Notre Dame in Paris.
• Quicklime binds concrete
• to hold up Hoover Dam
• and the Pantheon dome in Rome.
• Gypsum makes drywall.
• Alabaster makes lampshades.
• Terra alba coagulates tofu.
• Calcium in Tums and mineral supplements.
• Bigfoot prints cast with plaster of Paris.

Metallic stuff

• Just in case you didn’t know,
• your body is full of metal, mainly calcium.
• It’s in your blood, teeth, and bones.
• To qualify this strange but true fact,
• one must observe that calcium
• does not exist in the body in chunks or sheets
• but as calcium hydroxylapatite in teeth and bones
• and as calcium ions in blood plasma
• where, to function, nerves and muscles need them.