"A total of 47 samples were analyzed and selected from many different locations throughout the project site at various depths to obtain a general sense of precious metal recoveries that can be obtained by leaching with cyanide. Results from the cyanide shake tests follow:

Material Type Average Recovery
  Gold Silver
Majority Oxide 88.18% 80.54%
Mixed Oxide/Sulfide 80.07% 75.63%

Cyanide shake test procedures at McClelland Laboratories involved obtaining a split of the original reverse circulation drill sample pulps that were used for determining the initial fire assays. The minus 150 mesh sample splits were placed in centrifuge tubes containing cyanide solution and agitated on a shaker table for two hours. The solution was then analyzed by atomic adsorption for gold and silver, which was then compared with the original fire assays to determine recoveries."


These are impressive gold recoveries from the -150mesh (106 microns or .106mm grain size)...

However MDA also noted  "based on present understanding, the economic environment, and currently available information, the grades of overall mineralization at Cahuilla are likely not high enough to support a milling operation."

In other words, unless the ore can be milled to -150mesh economically, you will not see these kinds of gold recoveries....ie there is a milling cost associated with getting 80-88% gold recovery factors.

It would be of more interest to see what the test gold recovery factors are for coarser grain size samples that would not require milling.