Technical Data for PEARL.
name: Mabe PEARL is also known as a blister pearl.
it forms as part of the shell and looks like a blister
on the inside of the shell.
colour: Pink, silver, cream, golden, green, blue, black
colour of streak: White
mohs hardness: 3-4
specific gravity: 2.60-2.78
fracture: Concoidal or scaly
crystal system: Microcrystalline
chemical composition: 84-92% calcium-carbonate, 4-13% organic substances,
transparency: Translucent to opaque
refractive index: 1.52-1.66 Black: 1.53-1.69
double refraction: Weak or none
absorption spectrum: Not usable
fluorescence: Weak; not usable. Natural black: red-reddish