Geologist Dopers: Good sites for rock ID

Gday folks,
I bought a mineral and rock collection on ebay. It is rather vintage (the prices on the specimin boxes are 20c) and very very cool. A number of specimens have come adrift from their boxes so I’m trying to work out which ones go where. I also have a pile of unidentified loose specimens to name as well.
I have been googling madly and have had some success albeit hit and miss. So now I’m after some opinions on good websites I could use to aid in my quest.

Why not post some pics so we can help out.


Geologist Doper

Yeah. It’s not a subject we can take for granite.

And to think, students complained incessantly about IDing hand samples when I taught physical lab…now people do it for fun (I kid, I kid). Don’t know of any websites, but try looking at the Geology departments of universities. Many profs put their homebrew Mineralogy and Petrology lab manuals up nowadays, so the kids don’t have to pay for them.

If you really want to know how to do mineral and rock ID, it’s not that hard and can be really fun, plus you don’t need anything that you don’t already have around the house (OK, maybe a hand lens and some HCl). Buy a used copy of Manual of Mineralogy by Klein & Hurlbut or Dana’s Manual of Minerology (from which the H&K book is adapted). The edition doesn’t really matter much, as long as it’s within the last decade or two. Half Price Books and Powell’s often have good deals on old textbooks like this.

Hmmmm. I feel like posting a “rock of the day” thread.
Any how the lables on my boxes without rocks are:
Mangano Calcite
They are all from Australia

First lot of rocks without boxes pics here:
My camera is dying so had to use my scanner.

Minium will be orange-red
schorl is probably black and may show crystals (three wide possibly curved sides maybe alternating with three narrow sides)
manganocalcite is probably pink
pentlandite is a sulfide and possibly has a metallic lustre and a brassy colour (but could be tarnished)
stilbite is likely to be pinkish cream to white and probably crystalline

Mystery rock A is the stilbite
B is probably the manganocalcite
C is malachite as you said
D is ?, is rhodonite possible?
E ?, is gypsum a possibility?
F appears to be molybdenite
G possibly chalcanthite = bluestone = copper sulfate

A= Thankyou for confirming my suspision

I have been reading up on manganocalcite and the colour has been described as being from white to pink. Rock B is most definately brown. I am begining to wonder if it is a chunk of brown calcite that has been misslabled or that I’m missing it’s box.

Is molybdenite really realy soft (as in can be scratched with the fingernail soft)?

G = thanks that was prety much what I was thinking of.

I’m going to use info from this website to give you guys a bit more info on the properties of the specimens.

The last line and the misplaced “S” in the middle line suggest that siderite is one of the mineral options. Mineral B could be siderite - the colour probably fits better than it does the manganocalcite. There are several specimens in the collection that look like Broken Hill minerals (and minium is almost a certainty to be from BH) and a lot of the manganoan minerals from BH have a dirty red-brown colour.

Yes, molybdenite is really really soft, and has a perfect cleavage much like mica.

If G is copper sulfate then it will have a metallic taste, but it is poison so I would be pretty careful. It does occur in nature but is very soluble. I’ve seen it in Australian mineral specimen sets, often with crystals growing on a piece of stick

I have just found a loose lable for chalcanthite - Kalgoorlie W.A so you are on the money for G

I’m starting to suspect this one : is staurolite.

Could be crysoprase? I’m wondering if this is adventurine.

Possibly. The angle of the photograph doesn’t help

I doubt it; seems to be too bluish. Australian chrysoprase is all a pale green, possibly one shade paler than the skin of a Granny Smith apple. It’s very rarely seen with a rock matrix, which should be dark green or white. Vein edges are usually a powdery white (magnesite).

Don’t know enough about aventurine to offer much of an opinion. Aventurine should (must?) have a fleck in its body colour (which is often, but not necessarily, a mint green).