B14: John Shelford Opal Beds EarthCache
Hidden : 7/19/2014
Difficulty:
2 out of 5
Terrain:
3.5 out of 5

Size: Size: other (other)

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Geocache Description:

The opal beds trails provides easy access for those hoping to see opals and agates. It also has some great views and a mix of trails for people of all hiking levels. The hike from the trailhead to the beds is about 1.8 kms. The trail is a little overgrown in sections but is marked. I had to problem finding my way to the opal beds.

Note: You may want to bring bug spray with you.

History

The opal beds were originally staked by John Shelford in the early '80s and later turned into a reserve staking area for the public to try their luck finding opals. You can also find agate in this area as well.

Directions

At Eagle Creek Rd. turn right and drive up the hill for 400 metres.

Turn right on to a dirt road and follow this for 3.0 kilometres. Turn left on to Guyishton Road. After 400 metres the bottom end of the Eagle Trail starts on the right followed by an old stream fed fountain 50 metres further down the road on the right.

At 1.3 kilometres along the road stay right at the junction. Continue on a further 2.1 kilometres to the main parking lot and trailheads.

There are also signs along the way to let you know you are going the right way.

Opals

Opal is a form of silica; classed as a mineraloid. Opal is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl and basalt.

There are two forms of opal, common and precious. Common opal does not show the display of color exhibited in precious opal. The internal structure of precious opal makes it diffract light; depending on the conditions in which it formed, it can take on many colors. Precious opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the reds against black are the most rare, whereas white and greens are the most common.

Opal is the national gemstone of Australia, which produces 97% of the world's supply.

Formation of Opal

Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids , caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed.

At the Opal Beds

Once at the opal beds, you will notice there are a few areas that have been searched before. If you look at the exposed broken rock closely you will be able to see where the opals were being removed.

You may also find some very small opals still embedded in the rocks if you look closely. I was able to find several different types of opal at this location in only a 15 minute period. I was able to identify a few of them as milk opal.

Logging Requirements

Answer the following questions and email them to me through my profile link:

1) You will know you are at the opal beds when you see areas of rock that have been searched through. You will pass through a few obvious locations as you reach the coordinates. Describe the texture and colour of the rock that you see at one of these locations.

2) Why do you think opal formed in these rocks? (Hint: Answer can be found in the cache page, your answer from the previous question may help)

3) Were you able to locate any opals? If so, describe their appearance. Do you think it is common or precious opal that you found? Why?

4) (Optional) Post a photo of yourself at the location or any opal you were able to find.

NO





Sources:
http://www.princegeorgecitizen.com/opinion/columnists/amateur-geologists-will-love-the-john-shelford-opal-beds-1.1090002
http://en.wikipedia.org/wiki/Opal
http://www.opalsdownunder.com.au/learn-about-opals/advanced/how-opal-formed-geology-opal

Additional Hints (No hints available.)



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