Jewelry, Gems, & Minerals/odd rocks


black inside
black inside  

glass exterior
glass exterior  
I'm having trouble identifying what I've found.  Image 029 and 038 are magnetic "rocks" I find on my property.  They are very light, appear to have glass on the outside and are easily broken.  Once broken the interior is black and appears to have numerous crystals contained inside.  Image 001 and 004 are of a completely different type of mineral.  The piece is very dense and very magnet.  The smaller fragment was chipped from the end of the large piece.  I filed the end of the piece (no small task by hand) and once filed the interior is very silvery and shiney.  The photo could be better, but the outside honestly looks like it was melted then hit with a strong wind.

It appears I can only upload two images at a time.


Without having the actual sample to look at, your "rocks" appear to be pieces of slag, a common and sometimes pretty byproduct of metal smelting. When metal ore is processed and melted, impurities, such as molten rock, rise to the top of the melt and are skimmed off. When they cool they sometimes harden into pieces resembling glass or even look like meteorites. This will also explain the magnetism since part of the original molten ore may cling to these pieces. Do you live close to an old smelter or in an iron processing district? Even if not, broken up slag is often used as roadbase.  

Jewelry, Gems, & Minerals

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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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