The extraordinary Taj Mahal in Agra, India, is a famous symbol of love and devotion. Tremendous wealth was required to construct this monument. There is a direct connection to precious metals of the Incas and their ancestors – and particularly, to silver from the Potosí mine high in the Andes Mountains.
Sand surrounds us–and while it may seem in infinite supply, it is not. Currently, sand is being used up much faster than it is being replenished. Sand and gravel, collectively known as aggregate, are the most widely extracted solid materials on Earth. A recent report by the United Nations Environment Programme recognizes sand as a strategic resource–and one with looming challenges.