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Identity HelpWhere to send specimen for testing

18th Aug 2016 12:43 UTCJennifer Cindrich

Where cAn i send in rock specimens i found to find out exactly whats in them? I live in central texas.

18th Aug 2016 14:36 UTCDon Saathoff Expert

Hello Jennifer & welcome to Mindat!!

Since we do not know at what level in the hobby you are, before we attempt to answer your question I'd like to ask a couple.

Where in Central Texas do you live? My wife lived in San Antonio for ~50 years & hunted Texas for ~40 of those years.

Are you aware (by definition) of the difference between a 'rock' and a 'mineral'? A rock is a combination of minerals and if you have a rock we need to know at what level you want the analysis - whole rock for quantities of elements present or just the accepted name of the rock. If you are asking about a single mineral species in a relatively pure sample (homogenous) do you have enough sample to sacrifice a couple of milligrams or so?

And you could take a focused and well exposed pic of the sample, upload to Mindat's Identification forum and give us a shot at helping!! We're FREE!!

Don S.

18th Aug 2016 14:53 UTCDonald Lapham 🌟

Jennifer,

I second Don's suggestion to post a picture.

I also recommend Kerry Day. His service is $8 USD/Qualitative analysis. Please see the SEM-EDS section of his web site http://kaygeedeeminerals.com for details.

18th Aug 2016 16:19 UTCJennifer Cindrich

Thank you Don and Don.

I know is is calcite but I wanted to know all of the elements present. I have enough to sacrifice. I will post pictures also just for you guys to guess. I don't know how to rate myself as far as what level I am at as a rockhounder. I like it a lot and do it in all of my spare time. I have a degree in Environmental management and have taken some geology classes.

I can say I am a beginner at collecting florescent minerals, which is where my confusion is at presently.

The calcite pieces I have found on my property are fluorescent (purple and yellow), and phosphorescent with UV and regular white light. Some pieces are only calcite yet others are obviously other elements mixing in with it and I wanted to know what, besides the limestone some pieces are embedded in.

I love ya'lls website! I live in central Texas in Blanco county on the edge of the Llano uplift. Very cool rocks here!

18th Aug 2016 16:48 UTCKyle Beucke 🌟

Sounds like a bulk analysis might be want you want (would involve sending in a sample, maybe one ounce or so, and dissolving in acid mixture and analysis of individual elements with atomic absorption and ICP). As far as I know, there are standard packages of ~20 of the more common elements and/or you can specify particular ones (for example, I often send in samples for silver, copper, lead, antimony, etc.).

Florin Analytical Services does this. They have a $150 minimum order.

Others will probably know a lot more about this stuff, but there is one possibility. One caveat: Bulk analysis will tell you what is in the rock sample down to a low concentration, but not how it is distributed. Could be a tiny mineral grain that went unnoticed. If you want to know what is in a specific grain/crystal, microprobe, etc. would be an option. Con here is that it is a spot analysis, so you have to assume composition is uniform. Different methods for different purposes.

Kyle

18th Aug 2016 16:48 UTCJennifer Cindrich

-- moved topic --

18th Aug 2016 17:19 UTCMatt Neuzil Expert

If you are looking to identify other minerals, hardness tests, streak tests, etc can help. Post some pictures here and people might be able to help without needing analysis.

If you are curious why calcite fluoresces, i believe its most commonly uranium or manganese ions.

18th Aug 2016 17:43 UTCRob Woodside 🌟 Manager

Kerry will tell you what's in your sample down to about a per cent or so. That will often nail the species and if not point you in the right direction for rarer things. Unfortunately minute impurities, unseen by EDS, often cause the colours and fluorescent properties.

18th Aug 2016 19:23 UTCJennifer Cindrich

Thank you so much!

19th Aug 2016 00:05 UTCRobert Rothenberg

Hi all,

Just for the record, Kerry Day charges US $10 for an analysis. I have used his services often and have been very happy.

Bob

19th Aug 2016 00:24 UTCKyle Beucke 🌟

I second (third, fourth?) that, it is a great value and I often use his service for identifying minerals. He has gone out of his way to accommodate various requests.

The OP said she wanted to know exactly what is in the rock. EDS will tell you what the composition is, but on a specific spot, and there is a high lower limit if you are concerned with trace elements. Again, every method has its strengths and weaknesses. Bulk analysis will tell you if there is 50 ppm, etc. of some element in the rock/mineral.

Kyle

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