The “urze” heather (Erica lusitanica) appears several times in latin literature as it deserved in gold mining. In fact this plant was used by Romans to sieve fluvial sediments; after this process it was burned to extract gold from the ashes. You can find this plant in Corgas, a place with a breath taking viewpoint: from here you can admire the three-dimensional shape of a giant fold longer than 20 km.