MSGID: 1:317/3 6394c96c   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    EPOD - a service of USRA   
      
   The Earth Science Picture of the Day (EPOD) highlights the diverse processes   
   and phenomena which shape our planet and our lives. EPOD will collect and   
   archive photos, imagery, graphics, and artwork with short explanatory   
   captions and links exemplifying features within the Earth system. The   
   community is invited to contribute digital imagery, short captions and   
   relevant links.   
      
      
    Crystal Forms in Petrified Wood   
      
      December 09, 2022   
      
       TomMc_EPODImage2.WolverineLoopPetrifiedForest2022#2 (003)   
      
       TomMc_EPODImage1.PetrifiedWoodWolverineClose2022#1 (003)   
      
      Photographer:  Thomas McGuire   
      
      Summary Author:  Thomas McGuire   
      
      
       Grand Staircase National Monument is a spectacularly rich geologic   
      area in remote southern Utah. Within this monument,  Wolverine   
      Petrified Forest, shown above at top, features silicified (petrified)   
      tree trunks and sections. The variety of colors is caused by  iron   
      oxide and other oxide minerals.   
      
      
      In the bottom photo, the geometric forms at right are dark stained   
       quartz crystals that probably grew by groundwater deposition in   
      openings called “ vugs.” Quartz is extremely common, but visible   
       quartz crystals less so. When an  igneous rock cools and   
      crystallizes, quartz is the last common mineral to harden, so it   
      usually fills in the irregular openings between previously formed   
      minerals including feldspar, mica, amphibole and pyroxene. What   
      surprised me was the texture on this exposed surface. The radial forms   
      at the bottom of the photo are new to me, and I have yet to understand   
      how they formed. Photos taken in July 2022.   
      
      
      
      Grand Staircase National Monument, Utah Coordinates: 37.799633,   
      -111.214906   
      
      
   Related EPODs   
      
       Crystal Forms in Petrified Wood  Mt. Baker at Sunrise  Fossil   
      Find in Sicily, Italy  Arizona’s China Wall  Fossil Lake’s Legacy   
      at Wyoming’s Fossil Butte  Wagon Tracks from the Old West?   
       More...   
      
   Geology Links   
      
        *  Earthquakes   
        *  Geologic Time   
        *  Geomagnetism   
        *  General Dictionary of Geology   
        *  Mineral and Locality Database   
        *  Mohs Scale of Mineral Hardness   
        *  This Dynamic Earth   
        *  USGS   
        *  MyShake - University of California, Berkeley   
        *  USGS Ask a Geologist   
        *  USGS/NPS Geologic Glossary   
        *  USGS Volcano Hazards Program   
      
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      Earth Science Picture of the Day is a service of the  Universities   
      Space Research Association.   
      
   https://epod.usra.edu   
       
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