Martha

The Martha open pit gold mine is owned by OceanaGold Corporation and is located within the New Zealand town of Waihi. It was the first hard rock mine to be commissioned in the late 1970's following the resurgence of the New Zealand gold mining industry at that time. The Martha mine gold bearing ore is processed in a rural area, two kilometres away from the mine site, alongside the water treatment plant and waste rock embankments.

The Martha mine is an Open pit Mining Operation

As mining is carried out by means of open pit mining procedures at the Martha site, the waste rock and ore are crushed on-site before being taken along a 2.7 kilometre conveyor to the gold and silver processing plant. The gold treatment plant extracts gold and silver from the ore using conventional CIP (carbon-in-pulp) methods. The waste rock is used to build an earthen embankment to contain the mine tailings. A water treatment plant also exists near the gold and silver processing facility to treat excess water in the tailings dam before it is discharged.

Assay Samples Determine Which Area is to Mine ore at the Martha Mine

Before any rock is excavated from the Martha open pit mine, sampling of the rock is vigorously carried out with an accurate mapping of the gold bearing areas. Prior to the excavation of many areas it is first necessary to loosen the rock by blasting whereas other areas can be excavated with the use of a bulldozer alone. The ore bearing rock and waste rock are excavated separately and loaded onto haulage trucks that take it to the primary crushers, or to stockpiles.

Waste rock and gold bearing ores are able to be mined separately because the drill samples taken before any excavation is allowed are inspected in an assay laboratory for analysis. The assay result determines which areas are to be declared waste areas and which are to be mined as containing gold and silver. A cut off grade determines what makes the rock ore and what makes it a waste product. For example: if it has been determined the cut off grade is to be 1.0 grams of gold to a tonne of rock all rock with a higher grading will be regarded as being ore. All rock with less that 1.0 grams of gold a tonne will be written off as waste.

Gold has Been Mined in the Waihi Region for 300 Years

Gold has been mined in the Waihi Region of New Zealand for three hundred years, being discovered in the area during the 1800's. Underground mining was introduced into the region in the early 1900's, although, for the last quarter of a century most focus has been concentrated on exploration rather that mining activities.Although the 'old' Martha mine closed in 1952 it was not because of it running out of gold. The main reasons for the early closure was the low gold price at the time, the using of old worn out machinery, two world wars and an economic depression. The price of gold increased substantially in the 1970's and 80's which resulted in the identification of an economic gold resource that is still being worked at the Martha mine to this day.