On one day in January alone, around 40 former gold miners and widows crowded into a municipal office in…Lesotho…They were there to add their thumbprints to the names of nearly 7,000 others who are threatening the biggest class action suit Africa has ever seen…The men…worked deep underground for many years, often with insufficient protection. They inhaled silica dust from gold-bearing rocks and later contracted silicosis…The miners are led by Richard Spoor…A successful suit could collectively cost mining companies such as AngloGold Ashanti, Gold Fields, Harmony and global giant AngloAmerican billions of dollars, according to legal and industry experts…The big four mining companies declined to comment in detail for this article, saying they had yet to see the arguments, which Spoor is finalizing for the possible court filing.