Pocket Raman Spectrometers.

Does anyone have experience with products from DeltaNu (www.deltanu.com) - including the "Rockhound" and "ReporteR" hand-held Raman spectrometers. How well do they work, what is the discrimantion ability, pricing, etc... Since you get a laptop PC with every purchase, I suspect they are costly. This would be an ideal means of identifying a large number of minerals, especially in conjunction with the RRUFF database.

A presentation at the Rochester Symposium this year discussed the current effectiveness of these kinds of devices - and they don't appear to be currently even good enough to tell basic common minerals apart accurately. I think we'll have to wait for the next generation.

Jolyon

The live demonstration in the hospitality room at Rochester exhibited the shortcomings of these units. They are very unreliable under controlled conditions, nevermind out in the field. The unit used is useless for feldspars and a list of other species. It competently identified a prehnite, a cut stone in a ring, and a few other samples. It failed frequently. The default result seems to be "kyanite." If it is confused, it is kyanite!

For the price I heard that it had cost, you could buy a LOT of field guides.(and a good field guide used well would be much, much more reliable!)

Philippe.

It does work very, very well for quartz! Well....I guess my eyes do too, and they are free!!

Just like any other instrument or identification method, no one method does everything. The Raman spectrometer hits the sample with an intense monochromatic light beam. The Raman effect is an interaction with certain chemical bonds present in the sample that scatter a small portion of the light back as a frequency which is shifted (a different color) than the incident light. The display is a representation of the frequency shift pattern of the scattered light. This spectrum is representative of the chemical bonds present in the sample and for pure compounds is unique. The computer is used to store spectra of known compounds for matching against the spectrum of the unknown. Raman can be a powerful technique for mineral identification. Dr. Robert Downs of the University of Arizona gave a talk during the micromount symposium at the 2008 Tucson Show on his research project to determine Raman spectra for all minerals. See [rruff.info] for more information. I have been using a Raman Systems R-3000 for about a year and have had good results identifying certain minerals, especially colored gemstones. I am also familiar with the Ahura First Defender and Smith's Detection RespondeR RCI for hazardous material identification. I have come to conclusion that the method depends heavily on how good the library of known spectra is. The laser light frequency picked for the incident light source also affects what sample colors may or may not produce usable results. Overall Raman is a promising method. Instruments cost $15,000 to $20,000 but Ahura is rumored to be ready to market an instrument in the $7000 range.

Dr Downs talk gave a even and fair overview of the field and in particular what he and his students are accomplishing with it at U of A. My take on it was that he is hopeful that with continued microminiaturization of data storage, electronics and the increasing amount of baseline data on minerals and other substances, that a handheld will become more reasonably affordable and more reliable within the next decade . I personally left that talk, quite excited about this technology.

What Dr Downs is doing is admirable but we collectors and dealers need to know identities of our minerals now and not in 10 or 20 years when there may be a reasonally priced (?) Raman handheld unit available.

My approach has been to provide a quick turnaround x-ray diffraction service at reasoable price and offer it to anyone who needs it. XRD solves most cases but when needed I resort to microprobe, chemical analysis or other methods. I can be found on mindat, google etc. I am geared to the needs and budget of mineral people.

Thanks everyone for the response and discussion. I have used Raman, for research related tasks at work, on and off for the last 10 years, always with a contract at certain Universities - and always very expensive - the interpretation of the results is always challanging, and would be impossible without a good set of reference spectrum, on known materials, collected at the same time. I will have to agree with John's assessment that Raman is not ready for convenient mineral identification, the best is still XRD with EDS as needed. Maybe someday we will all be walking around with "Tricorders", but till then...

Jeff