FMF - Friends of Minerals Forum, discussion and message board

[zanthal]

I got this egg from a rock shop on the way to the Grand Canyon back in 2005.

I'm at a total loss as to what it might be.


Any help?

[zanthal]

This agate was listed at my local rock shop as "Ecstacia Agate" and the clerk called it "Exactia Agate"

Anyone familiar with it?

[zanthal]

Peruvian Serpentine?

[zanthal]

Is this some type of Selenite?

[zanthal]

Monzonite? Granite?

[zanthal]

Moss Agate? Serpentine?

[zanthal]

Moss Agate? Serpentine?

[John S. White]

Gypsum, perhaps, but selenite NO! ( https://www.mineral-forum.com/message-board/viewtopic.php?p=8933#8933 )
It appears to be the variety alabaster.

[Tracy]

Couldn't it also be onyx? A scratch test would tell.

[zanthal]

Alabaster ... that sounds familiar. I'm too young for my memory to be failing on me like this :0-)

Thanks for the input ... keep it coming, anyone.

[zanthal]

[John Cesar]

While Peter is the expert on Mexico I will jump in here and guess that this egg and the black and white egg are both calcite alabaster, more popularly known and promoted in rock shops as "Mexican onyx."

John

[Montanpark]

Hi,
first you should do is scratch test (and tell us which are harder than glass ;-), weaker then a copper mint, scratcheable with finger nails ) .. second test you could do is with acetic acid (or better if you have, a drop of 5 % muriatic) to identify the carbonates like calcite/aragonite /the 'alabaster' looks a bit like aragonite/calcite banded sinter. Any minerals showing bubbles with the acid are carbonates.

Only from viewing pictures without having more infos is almost impossible to identify unless someone knows the typical appearance of the material.

cheers
Roger
P.S. John, what is calcite alabaster? I only know alabaster as a dense form of gypsum. This may be a trade name for banded carbonates like 'calcite onyx' etc.

[Tracy]

[zanthal]

I'm real new to this. I equate my level of knowledge and experience to those on this site similarly to a 4th grader in school with first year college students.

I always appreciate opinions, I'm in the learning process


I have a small tumbled piece of Black Onyx from Mexico. I don't see any similarities to it and the eggs but I know that doesn't really mean much.

If you look at my thread called "Looking for help with identification" there is a link with photos of everything I have (limited as it is), including this Black Onyx

[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]