Bytownite Faceting Information

A source of tips and guides for faceting Bytownite. This belongs to the plagioclase feldspar group and is considered one of the rarest amongst the members.

Home Learning Center Jewelry and Lapidary Cutting Information for Specific GemstonesBytownite Faceting Information

By Jeff R. Graham

Bytownite Faceting Information

Bytownite (Feldspar)

Color: Pale yellow to brown
Moh's Hardness: 6-6.5
Refractive Index: 1.52-1.568
Critical Angle: 41.14°
Specific Gravity: 2.56-2.70
Cleavage: Perfect
Fracture: Uneven, can be brittle
Dispersion: .012
Heat Sensitivity: Moderate in my experience
Dichroism: Weak
Birefringence (double refraction): Weak to medium (.005-.01)
Crystal Structure: Triclinic

Treatments: Generally none

What I prefer to polishing with: Cerium oxide with a Spectra Ultralap.

Jeff's Comments: Cuts and polishes easily, use a medium fine lap like a 600 grit for roughing in because a coarse lap can sometimes aggravate cleavage. Cleavage usually is not a problem, sharp corners have a tendency to chip out sometimes during cutting.

Design Notes: About any Quartz design will work well. I prefer a deeper design and often cut Barions.

Design Links: Tzar - High dome will help improve color and sparkle

Jeff R. Graham

The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.

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Bytownite Faceting Information