In Cobriza, the high grades pockets run between 4-6 kg of Ag and 5-11 gr/ton of Au at the heart / center of the width of the vein. We even have found rich pockets with 38 kg of Ag and 270 grams of Au per ton. The rest of the vein grades are between 700 and 600 gram/ton of Ag and 1.5-3 grams Au; these grades were sustained throughout the entire period of previous mining activity
The launching project of Coral Silver, named Cobriza Project, an old spanish mine which opened in 1750 and has been in intermittent production over the years. The first modern studies over the mine were done by Olagaray and Madero calculating its potential in over 3,750,000 tons. Studies include Buen Paso 1996, FIFOMI, COREMI, two 43-101, the first was issued in 2003 by Dr. Peter Megaw; the second study was issued in 2008 by Dr. Lawrence Sookchoff. In 2006, Servicio Geologico Mexicano performed basic geology followed by trenching and detailed geology, by Minera Cascabel and SGM later that year financed a reserves certification program through a direct drive over the main structures. Since 2011 the company has been exploring through direct tunneling, drifts and footwall drifts; the commercial high grade ore has been sold to different smelting facilities. The project is located 125 km northeast of Mazatlan and 150 km west- northwest of Durango City, Durango Mexico. It lies in the center of the famous San Dimas mining district where high-grade gold-silver veins were discovered around the year of 1757 (Dahlgren, 1882). The district has produced an estimation of 9.5 million ounces of gold and 750 million ounces of silver, according to the 43-101 by Dr. Megaw.
Cobriza is an old Spanish mine that has had extensive workings done on it since the early 1800ʼs and the 20th century. Now, it is being studied, as well as having minor extractions since 2006; although it has not been explored with modern methods such as diamond drilling. During the current ownership, Cobriza has been explored by Basic Geology, Detailed Geology with trenching, and extensive sampling of workings and surfacing, direct tunneling over the main structure that concluded in the first positive reserves. In 2006, the Mexican Government financed ($40,000 U.S) a small study to show the value of Cobriza's reserves, which confirmed 10,000 tons with grades of Au 1.5 and Ag 622 g/ton.
The geophysical study conducted by Geologist O. Hernandez, depicts high grade mineral bodies, which can be seen in the pink and the red parts of the graph below.