It is still dark when we set out for Flores de los Andes, a lapis lazuli mine 4,200 metres up the mountains of Ovalle, central Chile. It is only accessible when the snow melts between February and April. The boys are wrapped in blankets in the back of a 4x4. Juan, a short, stout, weathered-faced miner, is with us. He speaks no English, I speak no Spanish. We communicate with hand movements.
We drive from coast to valley floor, and up dusty tracks. Then, as the sky lightens in the middle of the wilderness, alpine meadows rush up to bare, pointed peaks as we cross clear streams filled with leaping salmon. We pass mountain goats and herds of wild horses and the odd lone gaucho on a mule.
The land becomes bleached and barren, the track merely a path of crumbled rocks. From the top of the pass the valley stretches out behind us. My sons are stunned. The air is icy, dry; it's hard to breathe. Juan points to a rickety outbuilding, and beyond to a small coloured crack in the slope, like a door to Narnia. It is our mine. In this land of bleached browns and whites, it is a bright blue stain. Breathlessly, we head on up by foot. The air smells of sulphur. A huge boulder of ice blocks the entrance. The owner opens the mine only for large commissions, so much of the lapis lazuli in Santiago, used for jewellery and ornaments, is stolen from here by locals.
Juan has brought a sack for the boys to collect what they want. Excitedly they pick out the bluest, brightest rocks. In the past it has been ground to the finest powder and used to colour the frescos of Giotto, the pastels of Fra Angelico, the cloak of Christ and the veil of the Virgin Mary. It is quite something to stand at the source of such a colour. When it rains up here, every seven years or so, the flowers that spring up over the Flores de los Andes are blue, as if nature itself were leaving a clue.
Lindsay Hawdon's debut novel, 'Jakob's Colours', is published by Hodder and Stoughton (£14.99). Read more at therainbowhunters.com. Lindsay travelled to Chile with Cox & Kings (020 7873 5000; coxandkings.co.uk).Reuse content