Colorado Gold or just Pyrite?

[Rogerson785]

Several years ago I took a tour of the Mollie Kathleen Mine just outside Cripple Creek, Colorado, and at the end of the tour the guide lets everyone take a sample from the ore car. My sample was very nice; as it contained traces of Amethyst which the hard rock miner proclaimed that was always a good sine as gold and Amethyst were usually found near one another.


So, this past week while near the town of Leadville I discovered this piece, and I must say I initially thought it to be just another piece of pyrite. What do you think it is?
Gold?




The first sample is from the Cripple Creek area and the second sample is from the Leadville area.






These of course are pyrite, or fools gold.

[Rex_Tremende]

Looks like pyrite to me, owing the cubic structures there. But I am not a mineralogists, either.

Nice way to remember the trip, anyhow.

Regards,
Rex.

[The Wizard of BC]

The sharp, hard crystalline shapes lead me to think what you found is Pyrite.
Pyrite is a crystal with sharp edges and flat surfaces. Because of the flat facets it is also shiny and will reflect light well. It usually has a bright silver color.
Gold on the other hand is usually dull, with soft edges. It's color can be anywhere from dark brown to red to light green but is not normally found in the pure yellow gold color you see in refined jewelry.
Gold in nugget form is really a dull and uninteresting looking blob that you would easily overlook in favor of crystals or bright colored rocks.

One field expedient method of testing is to check hardness. Use a knife blade or pointed awl and push it into the surface of the crystals. If you can't dent the crystals fairly easily you probably don't have Gold. The crystals will probably break before denting. Gold will usually bend or dent long before it breaks. Pure Gold is usually soft enough to sink your teeth into. (remember all those old movies where someone would bite a coin to check if it was Gold?)

Also, the areas you found these samples were not known for Gold in nugget form. It is usually in ores and can't be seen with the naked eye until ground up and refined. Not that nuggets weren't found, it just wasn't normal.

Of course Barb T. will jump in here and totally prove me wrong. Geology is her real business and she will probably be able to tell you exactly what these are.

[Chas]

Nice way to remember the trip, anyhow.
Regards,Rex.

I think it is one of the best ways. Whenever we visit somewhere as a family, or on our own, we bring back a stone or rock or pebble or such. They all end up in a rockery in the back garden. When we moved house, the rockery came with us. Years of memories.

Good close-ups Chris.

Regards

Chas

[Ozark Ridge Rider]

The problem with "pyrite" is that, while the name is most often ascribed to iron pyrite, or fool's gold, there are a fair number of similar minerals which have pyrite as part of their name. A lot of them look similar, but some are pretty dark, some lighter, some with a colored sheen.

Saying pyrite is a bit like saying tartan, i.e. which one.

I've collected half a dozen different ones out of ore dumps around Cripple Creek and Ouray. Sometimes several in the same chunk of rock.

I can't really tell from your pics (probably my screen problem). Maybe Barb can straighten us all out.

[Riverkilt]

Steve's pegged it. Mined a lot of that stuff in the Idarado and never found any pure gold. It all came out in the processing. The stopes were like King Solomon's mines though reflecting light off pyrite and peacock copper - sometimes even fresh galena while it was still shinny.

The one piece of gold I saw at the mine - according to the assay office - was about the size of the head of a straight pin and looked like a saffron powder. You just don't see what's in the jewlery stores underground chasing veins.

But beautiful samples for sure.

Ron

[Jock Scot]

I think it is one of the best ways. Whenever we visit somewhere as a family, or on our own, we bring back a stone or rock or pebble or such. They all end up in a rockery in the back garden. When we moved house, the rockery came with us. Years of memories.

Good close-ups Chris.

Regards

Chas

I do that too! I think I will have to start again now though. When I visit my parents' grave,or any other special one to me, I always take a wee pebble from home to leave there on the grave.Why I do it I am not too sure ,but I always have.

[English Bloke]

... These of course are pyrite, or fools gold ...

Yes Chris, of course, I believe you... you just want it all for yourself don't you, you just don't want another gold rush. Quick lads, there's GOLD in them there hills...

Great pictures by the way.

As an aside, my Great Grandfather went to seek his fortune on the Klondike and came back with a silver dollar and a stuffed moose's head. I assume he had a good time.

[Jock Scot]

Yes Chris, of course, I believe you... you just want it all for yourself don't you, you just don't want another gold rush. Quick lads, there's GOLD in them there hills...

Great pictures by the way.

As an aside, my Great Grandfather went to seek his fortune on the Klondike and came back with a silver dollar and a stuffed moose's head. I assume he had a good time.

Don't forget that there was our very own Scots "gold rush" up here in the Highlands about 150 years ago, in the Strath of Kildonan.

[Barb T]

Yup - definitely pyrite. Both the color and the crystal forms give it away. Gold is really quite yellow in comparison - find a piece of good gold jewelry and put it next to the pyrite in your samples, and you'll see what I mean.

But, interestingly enough, Colorado pyrite from several districts is what's called "auriferous pyrite", meaning that it contains gold as an "impurity". In some locations, it's got enough gold in it to be mined as an ore of gold. But the gold still occurs in trace amounts.