This used to explain how gold is found for NCEA Level 1 Geography students.

1. The recipe for… GOLD Case 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 r eplace 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 n atural 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!

9. Gold and silver is found in Quartz veins Where could the quartz veins be?

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

11. 1.1 cont… Gold is found in q uartz 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 t op of many q uartz v eins . This is called the ‘ Martha load .’ The ‘load’ being the q uartz v eins .

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 a lluvial gold deposits are d redged (ground up from the riverbed) and p rocessed for gold. Up until 2 004 this happened at the G rey R iver Dredge on the W est C oast .

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 d rill holes down, looking for q uartz v eins and build mine s hafts (tunnels under the ground) to t ransport people and the mined rock. This occurres at Macres M ine in Otago, and G Cross Mine up until 1998 and F Cross Mine in W aihi today .

21. 3. Opencast Mining The 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 p it is dug and the r ock is taken o ut and p rocessed for the gold. This occures at M acraes Mine in O tago , and until 2 006 M artha Mine in W aihi .

23. 1.2 cont… What is one other way to collect gold that is similar to dredging? Gold panning

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 gold Mining 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 N orthland , T aupo V olcanic Z one and in C oromandel .