Short answers, pulled from the story.
Zinc is most commonly used as a galvanizing agent to coat iron and steel against corrosion, accounting for 55% of US zinc consumption in 2009. It also appears in brass alloys, alkaline batteries, zinc oxide sunscreens, anti-dandruff shampoos containing zinc pyrithione, and as the primary metal in American pennies since 1982.
Zinc is required for the function of over 300 enzymes and 1,000 transcription factors and is the only metal that appears in all enzyme classes. Roughly 2-4 grams are distributed through the adult human body, with key roles in immune function, DNA replication, protein digestion, carbon dioxide regulation, and synaptic plasticity in the brain.
Metallic zinc was isolated in India by 1300 AD, using a distillation process developed at Zawar in Rajasthan, with the oldest known man-made pure zinc from that site dating to the 9th century AD. In Europe, German chemist Andreas Marggraf isolated pure metallic zinc in 1746, and his procedure became commercially practical by 1752.
Zinc deficiency affects nearly two billion people in the developing world. In children it causes growth retardation, delayed sexual maturation, increased infection susceptibility, and diarrhea, contributing to the deaths of about 800,000 children per year worldwide. Deficiency is most common in populations with low dietary intake of animal products or high consumption of phytate-rich foods that block zinc absorption.
The name is attributed to Paracelsus, a Swiss-born German alchemist, who referred to the metal as zincum or zinken in his 16th-century book Liber Mineralium II. The word is most likely derived from the German zinke, meaning tooth-like, pointed, or jagged, describing the needle-like appearance of metallic zinc crystals.
China is by far the largest producer, accounting for 4,000,000 tonnes in 2023, followed by Peru at 1,400,000 tonnes and Australia at 1,100,000 tonnes. Large zinc deposits also exist in Canada and the United States, while Iran holds the largest potential reserves yet identified.