OXFORD 9000
📚 noun • entry_id 5054

calcium

/ˈkælsi.əm/
Meanings (ES + gloss)
calcio
The chemical element with atomic number 20: a soft, silvery-white alkaline earth metal which occurs naturally as carbonate in limestone and as silicate in many rocks.
Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis:[…]. The evolutionary precursor of photosynthesis is still under debate, and a n…
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