Rocks from Newman, WA. First Post

[gotrocks]

Hey Guys,

I was on a stint working in Newman, WA. As a surveyor I had plenty of time up my sleeve to go searching for rocks (a childhood obsession).
Thought I'd join up here and show photos of what I have.

I really dont know what they are, if you guys know please feel free to leave a comment :-)   

[gotrocks]

And my favorite

[gotrocks]

Ahh Let me upload a better qual of one, It just didnt do it any justice.

[Fullerton]

Welcome to the forum ... Very nice assortment you have there 

Love the red jasper and your favourite is my favourite too ... very interesting specimen. Wonder what the inside material is?

Last piece looks a section of quartz geode.

[darttrev68]

Hi

The first one looks like a red banded jasper - probably a banded iron formation - jasper is a fine grained variety of quartz. 

Number two is a quartz vein section with the crystals showing inward growth.

Number three looks like an agate - again a fine grained variety of quartz.

The last one is a quartz geode with a calcite core, some of which has dissolved away near the quartz contact.

Nice pieces. A few simple tests should confirm the ID. Scratch test for the quartzes and a drop of acid on the calcite - it should fizz.

Trev

[gotrocks]

Hey guys,

Thanks for the replies

Do you have a link to these tests? Scratch and acid? That would be great, now I'm on my way to see what you two have in gallery :-)

[darttrev68]

The scratch test is for hardness. Quartz is quite hard and will scratch most things. Anything harder than quartz is a gemstone. Try scratching a part of the sample on an old butter knife. If it is quartz it will leave a scratch on the metal. Quartz has a relative hardness of 7, while steel is around 5.5.

The acid test is to test if it is a carbonate. Place a small drop of hydrochloric acid (or you can use a bit of vinegar) on the sample and see if it fizzes. Calcite (and other carbonates) will react, while quartz and most silicates won't. 

Remember to do these tests on the back of the sample so that it doesn't show when the piece is put on display, or better still use a small bit that has broken off to test.

I hope this helps

Trev

[starsapphire78]

 Amazing specimes , really nice

[Gem Ranger]

Good ID on the geode Trev, that would mean all the calcite could be dissolved using hydrochloric acid leaving the geode intact with the quartz crystals creating a nice crystal cave look. The acid can be bought from a hardware store. Its commonly used to clean brickwork. Its strong stuff so use appropriate safety gear.

GR

[wallie]

What type of acid would you suggest? Hydrochloric, sulphuric, oxalic? Very interested in the answer as I have lots of quartz/amethyst crystals to clean and I've been using oxalic acid.

[MrSydney]

I love the Jasper - I haven't seen a sample such a strong dark red before!

[darttrev68]

Acids:
Hydrochloric is good for removing calcite and calcrete from samples. If there are other carbonates present it will also eat those. Diluted hydrochloric can be used to clean copper carbonates such as malachite and azurite, however it is only a very quick dip, fizz, then under running water. Can be bought at the hardware store in the pool chemical section. 32% concentration is the strongest. Warning - releases chlorine gas, so use in a ventilated area.
Sulfuric acid does much the same as hydrochloric, however it will leave soluble sulfate residues that are easier to remove than some residual chlorides from the hydrochloric. Diluted sulfuric is good for cleaning copper and other native metals.
Oxalic acid is used for cleaning iron oxide coatings off the samples. It must be kept under water or iron/calcium oxalate crystallises, which is next to impossible to remove. Care needs to be taken as it is poisonous. As it reacts with iron, use plastic containers and utensils. Oxalic is slow to act when cold, but will speed up the reaction if heated to around 80 degrees. Porcelain slow cookers are a good way to use the oxalic acid. Again this must be done in a ventilated area.

[MrSydney]

Darttrev - great summary and tips!!  Thanks!

[starsapphire78]

 I would leave the calcite , it's a nice addition to the, quartz , crystals