Colombian miner Touchstone Gold unveiled soaring losses after taking write-downs on the value of mineral interests.The Toronto-based explorer, which focuses on high-grade deposits in the Segovia gold belt of the Antioquia region in Colombia, reported a net loss of $15.1m (£9.7m) in the three months to June 30th, compared with a loss of $2.2m (£1.4m) for the same three months a year ago.Losses in the six months to June 30 were $16.4m (£10.5m) against losses of $5.4m (£3.5m) last time. Shares fell more than a third or 0.95p to 1.72p by 15:51 in London. During the first half, the company began its stage four drilling programme that was due to focus on three zones, but only one was drilled.Touchstone also achieved positive results from tests on several samples and made a surface discovery of a new gold zone. It holds 11 concessions totalling 24,699 hectares collectively known as the Segovia gold project.Last month, Chief Executive David Wiley stepped down to pursue other interests.PW