This item is series of cleavage plates of apophyllite cleaved in sequence from the same crystal selected to showcase the optical properties of apophyllite.  You will want a polariscope to fully appreciate the apophyllite cleavage plate sequence.  The first photo shows the apophyllite cleavage plate sequence unstacked viewed lying on cleavage surfaces (view is along the c-crystallographic axis) in transmitted plane polarized light.  The video demonstrates the optical properties of the apophyllite cleavage plate sequence with a polariscope.  The video begins viewing the apophyllite cleavage plate stacked together in transmitted plane polarized light.  We unstack the sequence of cleavage plates in transmitted plane polarized light.  Bringing in the upper polarizer in this view shows the crystal to be optically anomalous.  This apophyllite deviates from the uniaxial ideal illustrated by an extinction pattern likely caused by kinetic ordering-disordering of structural units.  Subsequent addition of a marble (converging lens) leads to the generation of biaxial optic axis interference figures.  However this figure is a bit odd as colored isochromes are lacking.  Not sure why that is to be honest, if you know let me know!  The second photo shows the cleavage plates stacked in transmitted plane polarized light, and the third photo shows the apophyllite cleavage plates with crossed polarizers at extinction.  The final three photos are in ambient light with a ruler for scale.  No nerdy video for this specimen as yet.

Each of these sequences are unique, as they are cleft from natural crystals.  Thank you, and check out some of our other items for sale.  We aim to provide the nerdiest mineral samples possible!  Combined shipping available for many items.