Serpentine

The main serpentine group minerals are antigorite, chrysotile, and lizardite. The main thing you need to know in order to distinguish between them is that chrysotile is fibrous, and antigorite and lizardite are not. Easy.

You should probably also know that chrysotile is both asbestiform and a form of asbestos. Touching it won’t hurt you, but snorting, licking, or otherwise ingesting it is maybe not so smart.

Physical Properties
Chemical formula Mg6Si4O10(OH)8
Class Phyllosilicate
Sheets of linked tetrahedra
Crystal system Monoclinic
Habit Fine-grained
Massive
Platy
Fibrous/asbestiform (chrysotile only)
Color Green
Yellow-green
Greenish white
Variable white
White
Hardness 3 to 5
Specific gravity 2.5 to 2.6
Cleavage Perfect (001) (antigorite)
None (chrysotile)
Fracture Flexible (antigorite)
Uneven (chrysotile)
Luster Resinous (antigorite)
Silky (antigorite)
Greasy (chrysotile)
Waxy (chrysotile)
Transparency Translucent
Streak White
Optical Properties
PPL Colorless
Low relief
Non-pleochroic
XPL Wavy extinction
Anomalous interference colors:
blues, greys, greens, yellows
δ 0.007
after Perkins, 317-318

Serpentine in Hand Sample

Chrysotile

Antigorite and chrysotile side by side

Serpentine in serpentinite from the Josephine ophiolite

Serpentine in Thin Section

Serpentine in plane polars

Serpentine in crossed polars

Serpentine, PPL
Serpentine, XPL

Further Reading

Antigorite at webmineral.com

Chrysotile at webmineral.com

Serpentine subgroup at mindat.org