Pennsylvania may not be the first place that comes to mind when thinking of gemstone mining, but the Keystone State has a surprising diversity of beautiful natural gemstones that can be found across ...
2004). This study presents robust LA-ICP-MS U-Pb data for zircon crystals from a mica schist and two pelitic paragneisses of the Jacareacanga Group. More than 100 crystals were analyzed for each rock ...
They are primarily composed of plagioclase (50± vol%), clinopyroxenes (25± vol%), and hornblende (20± vol%), with minor amounts of quartz (1± vol%), biotite (1± vol%), a few opaque minerals (1± vol%), ...
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