Sunstone Metals (ASX:STM) said drilling is set to begin in the March Quarter at Melonal, Copete, and Porotillo prospects at the Bramaderos gold-copper project in Ecuador, according to a Tuesday Australian bourse filing.

It also identified an exploration target of between 15 million ounces and 45 million ounces of gold-equivalent at the El Palmar project, also in Ecuador, consisting of 1 billion tonnes to 1.2 billion tonnes at a grade of between 0.3 grams per tonne to 0.7 g/t of gold and 0.1% to 0.3% of copper, for contained metal of between 10 million ounces and 27 million ounces of gold and 1 million tonnes to 3.7 million tonnes of copper.

The potential quantity and grade of the target is conceptual in nature, the filing added.

Its shares fell 9% in recent trading on Tuesday.