“A spectacular view of hundreds of penetration twins of fluorite from MSH. These fluorites are quite yttrium-rich (see child photo), which is interesting because I can't find any mention of other fluorite samples from MSH containing detectable yttrium by XEDS. These crystals are also just a few hundred micrometers from the phillipsite-K crystals identified on this specimen. Analcime in the lower portion of the image. J. Caleb Chappell image, Chris Emproto specimen, Ex. Jason Smith. Keywords: yttrium-rich fluorite, twins, twinning, twinned crystals, penetration twins.”

“A spectacular view of hundreds of penetration twins of fluorite from MSH. These fluorites are quite yttrium-rich (see child photo), which is interesting because I can't find any mention of other fluorite samples from MSH containing detectable yttrium by XEDS. These crystals are also just a few hundred micrometers from the phillipsite-K crystals identified on this specimen. Analcime in the lower portion of the image. J. Caleb Chappell image, Chris Emproto specimen, Ex. Jason Smith. Keywords: yttrium-rich fluorite, twins, twinning, twinned crystals, penetration twins.”