as stated in this news release ;

grade is significant and the mineralized structures tend to extend along strike for kilometres and to depths of up to 1,000 metres. To date, the Company has identified five mineralized zones with more than 50 quartz veins (having a total combined length of 9km) at the Tesoro Project and has carried out underground exploration and development work on three of these veins (C1, C2 and A4 Veins.) The veins are mesothermal, indicating that the vein structures may extend to considerable depths. The Tesoro Property has never been evaluated to depth, or to its full strike potential. This leaves a large potential for the discovery of additional mineralization. 

http://www.steliasmines.com/storage/news_releases/Sli-News-2010-02-Quantec-FINAL.pdf