Glossary of frequently used terms

Many of these geological terms are lost on people who aren't mining analysts or professional geologists. Here's a summary of some common mining terms that should come in handy when you are interpreting the latest statements or release from a mining firm.

Porphyry copper-gold deposits:

These are major contributors to new gold supply, yet most investors know very little
about them.



Just to explain briefly what a porphyry copper-gold deposit is - these are typically low
grade, bulk tonnage deposits which can only be economically mined using economies
of scale and relatively low cost open pit techniques.

In the unoxidized ores, the gold
occurs within copper and iron sulphides and cannot be mined by itself. Consequently,
copper-gold mines only do really well when both the copper and gold prices are both
healthy, but once the capital costs of building the mine and infrastructure are recovered
these mines can carry on for years, weathering the storm when either gold or copper
are lower in price.

Porphyry bodies in ideal cross section look like giant, upright lightbulbs. They can have
considerable vertical extent. They are made up of varieties of granite, formed by the
melting of the leading edges of oceanic plates, as they dive beneath continental
masses, inboard of collisional zones. They’re usually found a few hundred kilometres
from the coast. Porphyry copper deposits are found in the western USA, British
Columbia, and the west coast of South America, as well as in the Philippines and
Indonesia.

The copper sulphides typically occur in crisscrossing networks of quartz
veinlets within and throughout the porphyry rock. “Copper-gold” porphyries are rarer
than copper porphyries - the designation is arbitrarily set at >0.4 g/t Au. To recover the
metals porphyry ore is crushed and then most often processed using flotation. The
sulphide “concentrate” which is floated off is then shipped to a smelter where gold and
silver are recovered in addition to the copper. It’s important to recognize that cyanide
heap leach-type recovery such as used at many gold mines, is inappropriate for this
type of ore.

http://www.straighttalkonmining.com/docs/pdf/stom17.pdf

Assays:
Assaying is a means of determining how much metal is contained in a sample. Usually completed at a qualty controlled ISO 9001 laboratory.

Breccia:
Is coarse-grained sedimentary rock composed of broken fragments (clasts) of pre-existing rocks held together in a fine-grained matrix. Breccia is a mineralisation typical of epithermal deposits.

Drilling:
Typically completed with diamond drills




Induced Polarization (IP)
Method of ground geophysical surveying employeing an electrical current to detemrine indications of mineralization.

Stockwork veining
Densely distributed veining