Glass crystal model

 

F. Krantz (ca. 1900)
Glass model of a monoclinic crystal (ca. 20 cm) from a series.
A small glued label indicates: "I | Dr. F. Krantz | Bonn a. Rh."

Internal silk threads materialize the crystallographic axes and illustrate with the corresponding colours the dispersion of the optic axes and of the acute bisectrix for blue, yellow and red light.

private collection

image
the glass model as seen along the crystallographic b-axis
image
the glass model as seen perpendicular to the b-axis

image
top view of the model

image
detail of the label