Fluorite

I've had this sample soooo long I can't remember where I found it. I've always assumed it's fluorite because it's purple. There are very few minerals that are properly purple. Even fluorite is only sometimes purple. However lovely, fluorite is too soft and brittle to be a gemstone. Mineral collectors love it, though, because it's purple. This sample is about 3 cm across. I note that my doubts are cause by the elongate rather than cubic looking cleavage, but if it were perfect, some collector would have collected it instead of me.

Chalcopyrite out of vein...

This is massive chalcopyrite from Butte. It is lovely, isn't it? When in a rock, it makes up the "fool's gold" one hears of. However, when it's out of the rock and enters into the environment, such as flowing as gravel and sand in a river, it tarnishes and oxidizes rapidly. Panning for gold, only chalocopyrite very very very near its source site and in the river for a very very very short time still could be mistaken for gold. Sample image is about 3 cm across.

Chalcopyrite in vein...

Yes, good old chalcopyrite, the beginning collector's favorite. This from a vein of quartz with abundant chalcopyrite. It's from Butte, and might even have a bit of gold in it, but invisible gold.

Gypsum blades, on the other hand...

...don't make swordlike blades, but cm scale sawblade looking things. Also extremely characteristic. Saw a huge sample on the desk of the local District Attorney, who didn't know what it was and was hoping it would be worth more.
Not very. Pretty, but common.

Aragorn's Aragonite Blades!

Despite the filthy scanner, the aragonite crystals came out quite nicely I think!
The form of these blades is soooooooo characteristic. Since they're only about a cm or less long, I doubt if Aragorn could use them to save Middle Earth. But then, he's fictional, and the aragonite is REAL!

Ring around the Rock baby...

This remains my favorite sample of Liesegang banding.
Liesegang bands are frivolous additions to sedimentary rocks caused by the penetration -- evaporation -- penetration -- evaporation by water. Water that contains iron oxides leave red bands, and manganese oxides leave purple bands. Possibly, the same water has both iron and manganese, but the more mobile manganese oxide penetrates further. Bands can be found on layer surfaces or across layers. I note: my explanation doesn't agree with that on Wikipedia, but then there seems no consensus about these bands, so I prefer to go with my own opinion. Anyway, MY sample is prettier than THEIR sample!

From the kitchen sink of the Triassic

Yes, it looks like that nasty old sponge that just scrubbed out the oatmeal pot. In truth, it is an even older and nastier sponge, a fossil from the Triassic-Jurassic platform carbonates of the Pelagonian continent (an outpost of Pangaea). We don't know what the Mesozoic inhabitants would have used it to clean up, but I predict it was something nastier than oatmeal.

It's Turquoise because...

It's turquoise! Geo-Tourquise?
From somewhere in Arizona, though I have found bits and scraps here in Greece. You can generally find some along with copper mineralization. The bumpy-lumpy surface with a milky-glass interior is very characteristic. Perhaps not quite of gemstone quality, at least it's my very own piece.

GOLD!

To prepare our little booklet on gold, we need -- obviously -- a photo of gold. In particular, a photo of gold as it comes from a river after hours of strenuous panning.
I remembered that I had a small vial of the results of a panning day in Montana in 1973. All the water in the vial had long since dried out, and I was afraid to do anything more than add new water to the old vial, in fear of flushing the lot down the drain.
Then -- how to take a photo? Hah! As ever, my trusty world's cheapest scanner came to the rescue!

Listwanite

This listwanite is a surficial deposit on a bit of serpentinized harzburgite. I note that I've seen sites celebrating listwanite that looks like this as a semi-precious gem. But it's only ~2-3mm thick. The color, here lovely turquoise, is elsewhere red and yellow. As an alteration product of serpentine, itself an alteration of peridotite, it's like -- alteration squared. Anyway, this piece is from near Perivoli, and I imagine it might even be from the same deposit that Jan Brunn mentions as a potential gold ore.

The HUGE rock with really lovely light turquoise listwanite on the road to Vasilitsa is still waiting for several strong students to help me collect it!

Massive Coper Sulphides!

Definitely from the Butte Batholith! From one of pocket-filling samples taken on a field camp field trip.
Sulphide is chalcopyrite, here a brassy color, with crystals actually the large rectangular grains, such as upper right (crossed by crack), each ~1 - 3 cm long. The grey parts are quartz grains, lovely crystals. Note that colors in the quartz are due to internal reflectance from the bright scanner light. Makes it prettier, though!

Kyanite

I know that the kyanite metamorphic minerals collectors are after are blue, but these are very shiny deep navy-black. The turquoise - bright blue colors are from the scanner where the light is reflected from translucent crystals. Anyway, I did collect this sample, gods knows from somewhere. Most likely central Texas. Each crystal about a cm or a bit more in length.

Barite Rose

I visited a barite mine in California for an ore deposits mapping project, though this barite is not from there. I'm pretty sure I picked it up somewhere like a garage sale when I was in college. Anyway, these rose-shaped mineral aggregates of barite with sand, about 3cm in diameter, are actually an evaporite formation. Pretty, though, huh?

My oldest "Rock Baby"

Mike picked this up for me from my mom's basement in LA.
It's a piece of petrified wood from the National Park, where we visited on a family vacation in ~1956. I have a photo of myself with this, along with other rocks and "nature stuff" stuck onto a board for a second-grade science fair.