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Jewelry, Gems, & Minerals/Mineral Indentification

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Question
Streaks 1
Streaks 1  

Streaks 2
Streaks 2  
This stone was spotted half buried by the side of a highway in Southern California. I'm curious about what kind of stone it is and the cause of the streaks in the stone.

Answer
Hi Amy,
Unfortunately your pictures are very fuzzy and I can only postulate or speculate about your rock. It looks like that you have found a piece of "graphic granite". A good place for these type of rocks in Southern California is the Raniona Pegmatite district in and around San Diego County.
The streaks you are seeing is the mineral quartz (SiO2) that crystallizes simultaneously with potassium feldspar or orthoclase (KAlSi3O8) deep underground in a magma chamber. Quartz would be the clear streaks and the pink looking mineral is the orthoclase. Since these two minerals start to unmix as the grow in the molten rock, quartz has the tendency to crystallize in elongated streaks. In Southern California these type of rocks can contain gemstones. Famous are blue and watermelon tourmaline in the Pala District of Southern California.
Hope this helps!

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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