Separation of Sanidine Crystals in Pumice/Dacite/Rhyolite

  1. Test each fraction for the presence of sanidine.

    • Use peppermint oil to find the fraction with enough Sanidine crystals needed for the experiment.

  2. Determine fraction to continue.

  3. Resieve chosen fraction

Separating the feldspars from the rest of the crystals and glass is important for obtaining a clearer picture of the amount of feldspars that are present in the sample. When the feldspars are magnetically separated, you’ll be left with a potential mix of sanidine, plagioclase and quartz.

  1. Magnetically separate feldspars from glass and other crystals.

  2. Leach crystals in 15% HF for 5 (6-8 mins) Minutes in the large ultrasonic bath

    • Leach only one sample at a time.

  3. Post leach, let crystals sit in the sonic bath for 2 hours.

After leaching and a long session in the ultrasonic bath, it is important to resieve the sample because the HF will alter the size of the grains and the ultrasonic bath will break apart crystals. Select a representative fraction to pick the grains.

  1. Resieve fraction

  2. Conduct Heavy Liquids for Sanidine separation

  3. Pick Sanidine crystals from float.

  4. Pick plagioclase crystals from sink. * May need to frantz quartz from the plagioclase fraction if unable to disern between the two.