FMF - Friends of Minerals Forum, discussion and message board

[John Cesar]

Roger,

While I find the terminology confusing like you, back in the good old days I remember both calcite and gypsum being attached to alabaster like adjectives. Since we are dealing with soft carving materials, the name alabaster probably was a catch all for both minerals. Anyway, around here today the trade name mexican onyx is applied to what is typically banded calcite.

John

[zanthal]

Okay, results of scratch tests on the eggs:

I used the awl point of my swiss army knife (stainless steel) to scratch each. I'm going to refer to these by picture filename to avoid confusion.


T000031-.jpg = Easily scratched. Scratchings tended to crack off in small flat chips.

T000030-.jpg = Also easily scratched, scratchings were more uniform and smaller than #31, almost sandy.

T000032-.jpg = Same as #30, except perhaps it was even slightly easier to scratch.

[Debbie Woolf]

[zanthal]

I compared T000030-.jpg to some pictures of Calcite Alabaster and they are very similar.

And considering I purchased them not very far north of the Mexican border, it makes sense.

[zanthal]

[zanthal]

Thank you very much everyone, by process of elimination I've been able to identify everything I was unsure about.

T000009-.jpg that piece of agate is up in the air but I'm wondering if the rock shop I visited invented a new name for something. It was being sold as Exactia/Ecstacia Agate.

[Pete Modreski]

Zanthal, I just wanted to add an extra suggestion for you for getting help with other questions in the future. You might also get some good help by joining this "Rockhounds" email listserv, how to do it is described on their website:

Rockhounds@drizzle Mailing List
Subscription Services:
https://lists.drizzle.com/mailman/listinfo/rockhounds
List Usage Policy:
https://rockhounds.ning.com/page/list-rules

There, you can also post photos on their associated website (rockhounds.ning.com) which people can view and comment on. There are a lot of well-informed people on that group too, and you'll find that their interests are geared a lot more toward "all kinds of rocks, minerals, fossils, gemstones, and polished specimens", whereas as you will probably be noticing, the Fabre Minerals Forum is more focused on collectors interested in crystallized mineral specimens. Though as you've seen, the members are still quite willing to do their best to offer advice about "any kind of rock".

I'll just add a few of my own comments about your specimens:
Your #23 and #33 do look most like serpentine.
#27, showing a few small areas of white banded agate, I would guess is overall a type of "moss agate", and presumably will test as being quite hard (can't scratch with steel).
#30 is certainly the typical "Mexican onyx", a banded type of travertine, hence composed of soft calcite.
#31 I would have called this some type of jasper, with mottled colors. But if jasper it should be hard, and you reported it scratched easily, so... don't know what to say, just some type of mottled-texture rock.
#32 looks like it could be some type of banded marble--composed of calciite, hence should be soft.
#9, the names "Ecstacia" or "Exactia" agate don't ring any bells for me. It looks like some type of brecciated jasper.

Best wishes and good luck to you,
Pete

[zanthal]

Well it scratched easily based on my very limited experiences with scratching rock. I don't have much to make a comparison of scratching difficulty.



Egg #31 was harder to scratch than the other two eggs, this is true.


Thanks for the opinions and those links, I'll give them a look