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Jewelry, Gems, & Minerals/Help Identify Tumbled/Polished Stone


Blue Stone 1
Blue Stone 1  

Blue Stone 2
Blue Stone 2  
Hello,  I found this Stone with some other rocks my Great Grandpa polished Over 20 years ago.  I was wondering what type of stone it is.  
I read some of your other questions where you mentioned that it is difficult to identify types of rocks by a picture.  So I tried to take as good as Pictures as I can.  I did them in natural light, L.E.D light and U.V.!  I also took a 60X Zoom on the surface of the stone.  I hope that it helps and makes it easier for you.

Hi Angie,
I really like the effort you put in taking the pictures and they are of high quality with good resolution. However, polished stones have an additional draw back despite of the pictures. Polishing removes identifying marks such as crystal faces and fracture planes which are extremely useful in identification. To help you further, would it be possible to do the following two simple tests with your stone that could be very revealing.
#1 Does your stone scratch glass? Drag it across a piece of flat glass while pushing on the stone. Do you have to push hard or did the stone leave a scratch easily without much effort? Or is there no scratch at all? (Make sure there is a scratch on the glass by checking with your fingernail. If this is just a powder streak that you can rub off then your stone did NOT scratch the glass)
#2 Specific Gravity. This is a little bit more involved. You will need to get a scale that measures grams and has a resolution or readability of at least 0.01g. You will also need a small plastic cup, a piece of fine string or thread, and some water (tap water is fine).
Procedure: 1. Weigh the stone and record weight exactly. 2. Fill cup with water (enough to submerse the stone, but with room to spare) place on scale and tare scale to "0". 3. Tie string to specimen, and while holding the string submerse the specimen in the cup of water on the scale. Make sure your rock is completely submersed but does not touch the sides or bottom of the cup. Read this weight very carefully and record which is the buoyant force of your specimen and is equal to the volume of the specimen. 4. Divide the weight of the rock by the reading of the buoyant force of the rock which is the specific gravity of the specimen in g/cm^3.
If you could email these two results I might be able to tell you more.

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Uwe Richard Kackstaetter, Ph.D. (Dr.K)


I can answer questions concerning minerals, mineralogy, gems, metals, and anything that has to do with geology. However, I am NOT a jeweler. Questions about values, settings, gem stone cuts and appraisals are best directed to other experts on this site. I can however aide in the identification of unknown mineral materials. As a public service and part as training for new geoscientists, our university department provides FREE mineral identification for individuals. Please contact me for details or go to for details..


I am a professor of applied geology and mineralogy with many hours of field experience. Furthermore, I enjoy recreational gold prospecting and mineral collecting. As a professor I am engaged in research concerning minerals and their occurrence.

Member of the GPAA (Gold Prospectors Association of America) as well as the Association of Environmental Geochemists. Member of the GSA (Geologic Society of America) Member of the AIPG (American Institute of Professional Geologists)

Here is a small sampling: Mineral-rock handbook: Rapid-easy mineral-rock determination : written for anyone interested in minerals and rocks - Proctor, Peterson, and Kackstaetter;Macmillan Pub. Co. (New York and Toronto and New York) Physical Geology Laboratory e-Manual [CD-ROM], Kackstaetter, Earth Science Education LLC Colorado Front Range Self-guided Geology Field Trips, Kackstaetter,

Ph.D. in Applied Geology and Mineralogy. I am actively teaching courses in mineralogy and a variety of field courses with mineral collecting opportunities. Background in precious metal exploration.

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