You are here:

Geology/unusual rock



hello, we are in Pa, and found this rock in the woods near by, could you please tell me what it is, I couldn't find nothing on it

You are quite right this is an unusual rock; actually at least two different types of rocks.  I can tell you that the red rock is hemititic (red color) quartz.  The other rocks I can not identify from the pictures; without hardness, streak, density of the rocks.  The rocks are metamorphic; therefore, you must have found them east of central PA.  The white rock could be plagioclase (feldspar) but without seeing it I can't tell for sure.

Plagioclase has a hardness of 6 - 6.5 (cannot be scratched by a knife blade Mohs hardness of 5)but can be scratched by quartz(glass which is mostly made up of quartz)which has a Mohs hardness of 7. Plagioclase has a vitreous luster (which means pearly) and a white streak (when scratched on porcelain.  White is a very typical streak so this isn't going to help you.  Plagioclase has a specific gravity of about 2.65 which is the same as quartz so it isn't real heavy (probably won't help either). The other potential tell-tell sign are the striations.  Plagioclase very typically has striations much like on your rock.  These are weathering phenomenon but are common.  Below is a reasonably good example of striation on Plagioclase.  You might also try the second link below which shows several.

I can say with reasonable assurance that these two quartz and plagioclase did not form together but were/are now cemented together by hemotite FeOx.  

Hope this helps.



All Answers

Answers by Expert:

Ask Experts


Joe Norris


I am an economic geologist. An economic geologist does mineral evaluations and appraisals of mineral or mining properties. I can tell you if your deposit has value - remember that a mineral deposit, no matter how good, only has value when mined. Any value assigned to a mineral deposit, in the ground, is only the speculative value that deposit.


I have been a economic geologist for most of my 35 year career. Although I have done work in perhaps 45 states and numerious countries much of my work has been in Appalachian coal, intermountain west gold and silver, and Arizona uranium.

Past President of the Virginia Section of the American Institute of Professional Geologists and a certified geologist in twelve states.

BS Degree from Eastern Kentucky University. Work on MS Degree @ Eastern Kentucky University, Colorad School of Mines & Marshall University Numerious short courses on the value of mineral deposits and how to value same. Also several short courses dealing with the different types of geologic processes; sedimentary, igneous, metamorphic along with the mineral associated with each.

©2016 All rights reserved.