PLEASE NOTE: Gates close at dusk. There is a handwritten sign that says "NO DOGS" but on the information board it says "Dogs under control", so we'll leave it to you to decide.
You will need to undertake a circuit around the established walking route to a number of points of interest and you will need to answer questions at certain points to claim the cache.
There are other caches you can do in this area; Golden Cross GC1R47Y; Golden Cross walk GC1YCYA; Maratoto Track Views GC1YCXN.
View of the old pit at Golden Cross - now planted with trees
History of the Golden Cross Mine
Gold was first discovered in the Waitekauri Valley in 1875 and here at the Golden Cross mine in 1892. Between 1895 and 1920 the Golden Cross underground mine produced nearly 160,000 tonnes of ore to yield just over two and half tonnes of gold. After the mine closed the site facilities and the town disappeared as its 400 people moved on and the area became farmland.
In 1980 a prospecting license was issued to Cyprus Gold and an exploratory programme began in 1981. Following encouraging exploration results a mining licence was issued in 1990 and in December 1991 a new era of mining began. Mining was by underground and open pit methods. The higher grade ore underground yielded 6-7 grams of gold per tonne of ore mined. The open cast produced an average of 2.5 grams per tonne.
The Coeur d’Alene Mines Corporation purchased Golden Cross in March 1993 in an 80/20% joint venture with NZ company Viking Mining Ltd. Between December 1991 and April 1998 this mine produced a total of 18 tonnes of gold at an average grade of about 4 grams per tonne. The mine also produced just over 52 tonnes of silver. 5 million tonnes of ore were mined during this period. In total from 1895 to 1998, Golden Cross produced just over 23 tonnes of gold. The mine officially closed in December 1997 with some remnant underground mining continuing until early 1998.
Golden Cross was the first modern mine in NZ to move into planned closure and final rehabilitation.
Geology of the Golden Cross Mine
Some of the oldest rocks in the area are andesitic lava flows and are between 8 and 22 millions of years old. During the Miocene Period, a thick sequence of volcanic lavas, breccias and tuffs of generally andesitic composition was deposited to form the bedrock of the Waitekauri Valley and surrounding districts. Some considerable time later earthquake activity formed numerous near-vertical planar fractures in the bedrock which became channels for large volumes of ascending geothermal water. The old land surface, high above the Waitekauri Valley, would have resembled Rotorua, with hot pools, steaming ground, and geysers.
As the dissolved mineral-rich water ascended, cooled and the pressure released, many minerals came out of solution. They deposited or crystallized on the sides of the fractures. The predominant minerals were quartz and calcite. Gold and silver crystalized as electrum, native gold and acanthite . The geothermal fluids also altered the chemistry of the rocks they passed through,forming minerals like pyrite, adularia feldspar, calcite, chlorite and illite clay. Many of these mineral-filled fractures (or veins) intersected to form a complex lattice frame-work deep underground.
Millions of years of erosion removed hundreds of vertical metres off the volcanic rock sequence and progressively exposed the quartz vein lattice. Being relatively resistant to erosion, this lattice caused an ancient topographic high. Cold surface ground waters percolating down caused oxidation reactions in the andesite, changing it from a blue-grey to an orange-brown colour through the oxidation of pyrite to limonite.
Extremely violent rhyolitic volcanism during the Pliocene epoch resulted in thick, welded ignimbrite deposits covering the Valley. These filled in old river valleys. Erosion continued to lower and shape the valley. Distant volcanism deposited several thick layers of volcanic ash over the area.
Once you complete the following EarthCache requirements you can post your find without delay, as per the EarthCache guidelines. You will also need to verify your find by sending us a message with your answers to these questions and we will answer in due course:
1. Use the text "From Boulders to Bullion - GC23BVC" in your email.
2. The published co-ords will take you to a structure. What is this structure and what was it used for?
3. How many steps are there in process of turning boulders into bullion?
4. Proceed up the marked route to the lake. What is the elevation at water level here?
5. Standing at S 37° 19.763 E 175° 47.214; what is the dominant feature here and what created it?
6. Standing at S 37° 19.637 E 175° 46.987; what is the dominant feature here and what created it?
Please DO NOT post answers with your log.