Crystallex International (KRY.TO) said on Tuesday it had filed a second appeal in an attempt to reverse the Venezuelan environment ministry's denial of mining rights at its Las Cristinas gold mine.

The Canadian company said it had filed a rebuttal with the country's minister of the environment and natural resources. A previous appeal to the ministry's director general of permitting was denied last month.

Crystallex's long-held plans to develop the massive Las Cristinas deposit, in the state of Bolivar in southeastern Venezuela, were dealt a huge blow in April when it was told its permits were being denied.

The company's shares have lost half their value since late April, and were up 1 Canadian cent at 79 Canadian cents on the Toronto Stock Exchange on Tuesday.

Venezuelan Environment Minister Yuviri Ortega has since said the country will not award permits for open-pit mines and will not allow companies to look for gold in its vast Imataca forest Reserve, where Las Cristinas is located.

Las Cristinas, one of South America's biggest gold deposits, has reserves of 17 million ounces of gold.

The minister has 90 business days in which to issue a decision on the appeal, the company said. ($1=$1.02 Canadian) (Reporting by Cameron French; Editing by Bernadette Baum)