ClipArt ETC
"A positive biaxial interference figure with the principal sections nearly corresponding to those of the nicols. The arrows indicate the movement taking place upon inserting a quartz wedge above the section." -Johannsen, 1908

Biaxial Interference

"A positive biaxial interference figure with the principal sections nearly corresponding to those of…

"A biaxial interference figure showing the emergence of an optic axis. The arrow indicates the movement taking place upon inserting a quartz wedge above the section. The mineral is augite. (+)." -Johannsen, 1908

Biaxial Interference

"A biaxial interference figure showing the emergence of an optic axis. The arrow indicates the movement…

"A negative biaxial interference figure. The arrows indicate the movement taking place upon inserting a quartz wedge above the section. Epidote. (-)." -Johannsen, 1908

Negative Biaxial Interference

"A negative biaxial interference figure. The arrows indicate the movement taking place upon inserting…

"A positive biaxial interference figure. The arrows indicate the movement taking place upon inserting a quartz wedge above the section. Olivine. (+)." -Johannsen, 1908

Positive Biaxial Interference

"A positive biaxial interference figure. The arrows indicate the movement taking place upon inserting…

"Movement of the left bar...upon rotating the stage to the right, and movement of the colored rings upon inserting a quartz wedge." -Johannsen, 1908

Crystal Movement

"Movement of the left bar...upon rotating the stage to the right, and movement of the colored rings…

"A positive uniaxial interference figure. The arrows indicate the movement taking place upon inserting a quartz wedge above the section." -Johannsen, 1908

Uniaxial Interference

"A positive uniaxial interference figure. The arrows indicate the movement taking place upon inserting…