1

The recipe for…

GOLDCase Study: Martha Mine - Waihi

2

1.1 What does gold look like in the environment?Gold is an element (Au) and exists by

itself. It is not something that is made from a mixture of other elements. It is a non-renewable resource, as it can not replace itself in any way.

Gold can be found in different areas, but the way it is found and what it looks like depends on the natural processes that have acted on the gold.

3

Gold is found in hard rocks, along coast lines and in river beds.

Gold that is found along coast lines and river beds was once attached to rocks in the land. Over time the gold has been eroded by wind and rain (weathering) and washed into the rivers and carried along the coast line. Some particles of gold are big nuggets, and some will be small fragments, more like dust.

4

Describe to the person how you make

jelly…

5

In areas where there has been volcanic activity the gold has been through another process.

Gold, along with other minerals, has been dissolved in hot magma and boiling hot water that surrounds magma. The magma and boiling water slide into the cracks under the ground – fault lines and fissures, filling these up. As the liquid moves away from the heat source, the liquid solidifies, leaving what we today call quartz.

6

Where is the magma?

7

Why has everything gone all jaggered?Where are the fault lines?

8

Quartz is a mineral like gold, and gold and silver is found with quartz.

So, mining companies look for quartz veins to help them find the GOLD!

9Gold and silver is found in Quartz veins

Where could the quartz veins be?

10Lots of gold to be found!!!!!!!

11

1.1 cont…

Gold is found in quartz veins.

They are called ‘veins’ because… the quartz is like a thin strip running through the other rock formation, similar to the veins in our body.

12

Cross Section of Martha Mine

Quartz Veins containing gold and silver

13

Birds eye view of Martha Mine

14

1.1 cont…

Martha mine is located on top of many quartz veins. This is called the ‘Martha load.’ The ‘load’ being the quartz veins.

15

How do we get the…

GOLD?

16

1. Dredging rivers that have alluvial gold deposits in them

The Grey River Dredge on the West Coast closed in 2004.

The river floor is ground up, and deposits are taken out of the river, and then processed for gold.

17

1.2 What are the different types of gold mining?

1. Dredging – when alluvial gold deposits are dredged (ground up from the riverbed) and processed for gold. Up until 2004 this happened at the Grey River Dredge on the West Coast.

18

2. Underground mining

The Golden Cross Mine was an underground mine and an opencast mine. This mine was closed in 1998 and is now being rehabiltated.

Miners would drill down making shafts, and then they would drill horizontally looking for quartz veins.

19

2. Underground mining cont…Preparation for underground mining began at the Favona mine in Waihi in 2005.

Underground mining began at the Macraes Opencast Mine in Otago in 2006.

20

1.2 cont…2. Underground mining – is when

miners drill holes down, looking for quartz veins and build mine shafts (tunnels under the ground) to transport people and the mined rock. This occurres at Macres Mine in Otago, and G Cross Mine up until 1998 and F Cross Mine in Waihi today.

21

3. Opencast MiningThe Martha Hill mine operates an open pit. This will be closed in 2006. Macraes Mine in Otago is another open cast pit still operating so this now has operations above and below the ground.

22

1.2 cont…3. Open cast mining – a big pit is dug

and the rock is taken out and processed for the gold. This occures at Macraes Mine in Otago, and until 2006 Martha Mine in Waihi.

23

1.2 cont…What is one other way to collect gold that is similar to dredging? Gold panning

24

The ore is blasted

Trucks transport the ore

The ore is processed and turned into gold

25

Gold deposits

Which of these areas are being mined?

List some reasons for why not all deposits are being mined.

26

Gold deposits

Which of these areas are being mined?

List some reasons for why not all deposits are being mined.

27

1.3 Exploration to find goldMining companies are constantly

looking for more gold deposits that they can mine because… the current mines’ gold supplies will eventually run out or be to deep to physically to mine.

Mining companies are currently carrying out exploration in Northland, Taupo Volcanic Zone and in Coromandel.

28

1.4 The location of New Zealand’s different gold mining operations Locate and label gold fields and gold mines in New Zealand MINES- Golden Cross Mine- Martha Hill Mine- Grey River Dredge- Macraes Mine- Favona Mine

GOLD FIELDS- Otago Gold Field- West Coast Gold Field- Coromandel/Hauraki Gold Field

Write beside each mine whether it is still in operation or when it closed.

Draw a simple sketch to illustrate the kind of mining that occurs at each mine

Use an atlas to locate and label the Cameron Mountains and the Richmond Ranges which have gold deposits in them.

29

Gold mining in New Zealand is located in… Otago, Coromandel and the West Coast.Exploration is occurring in… Northland, Taupo Volcanic Zone and further exploration in Coromandel.

Describe where gold mining is located and where exploration is occuring for gold in New Zealand.

Underground gold mining is located… in Waihi at the Favona Mine, and at Macraes Mine in Otago.Opencast gold mining is located in…Otago at Macraes Mine and Martha Mine in Waihi which closes in 2006.River Dredging for gold… use to occur on the Grey River on the West Coast until 2004.

Describe where different gold mining is located in New Zealand and whether they are still operating.

Gold deposits are found in the Cameron Mountains and the Richmond Ranges but are possibly not mined because…. these areas have poor accessibility and they are a part of Regional Parks which means they are protected so mining is illegal.

Describe where gold deposits are found in New Zealand that are not currently being mined and give a possible reason for this.