Jewelry, Gems, & Minerals/Rock I have

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Whole rock
Whole rock  

Corner
Corner  
Hi, I have a rock that was dug up  in central North Carolina and I'm curious if you could give me any advice as to what it is. It is very dense and solid. It weighs atleast a couple pounds and it relatively small; very dense for the size. There are parts that are shiny almost like gold, and some that are almost black. I held a liter to a corner of it, and it looks like silver. Any help is appreciated.  I Have attached a picture. Thank you.

Answer
Unfortunately the pictures tend to be somewhat fuzzy and it is difficult to see any details. Are there any striations or visible bands on the rock? The silvery mineral is most likely muscovite mica, which appears in tiny flakes in rocks and is often mistaken as silver or even gold because it is rather sparkly.
In order to estimate the density as unusual, get a large hanging scale, such as a fishermen's scale or butchers scale with a hook. Tie a tough fishing line to your sample, and hang the other end of the line on the scale hook. Then measure weight, which is Wa, or Weight in air. Needs to be in grams. If in lbs, you will need to convert: multiply lbs by 453.592. Then submerse the sample hanging on the fishing line in a bucket of water. Make sure its free floating, doesn't touch the bottom or sides and doesn't peak out above water level. Again measure weight in grams, this time in water or Ww. The accurate density of your rock can be calculated as Density = Wa / (Wa - Ww). Anything below 3.5 g/cm^3 would make it a more or less unspectacular common rock. Densities above 3.5 g/cm^3 might indicate something special. In this case, write me again or maybe with some higher resolution pictures.

Jewelry, Gems, & Minerals

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

Expertise

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 http://college.earthscienceeducation.net/MIN/MINID.pdf for details..

Experience

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.

Organizations
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)

Publications
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, http://www.scribd.com/doc/27175290/Colorado-Front-Range-Self-Guided-Geology-Field-Trips

Education/Credentials
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.

Past/Present Clients
Numerous!

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