If you lick it (everybody does) and it tastes salty, it’s halite. Unless it’s only salty because a lot of people have handled it, in which case ew.

Physical Properties
Chemical formula NaCl
Class Halide
Crystal system Cubic
Habit Cubic crystals
Often massive or granular
Color Colorless or white

If impure, may be shades of red,
blue, purple, or yellow white

Hardness 2.5
Specific gravity 2.16
Cleavage Perfect cubic {100}
Fracture Conchoidal
Luster Vitreous
Transparency Transparent to translucent
Streak White
Optical Properties
PPL Colorless
Low relief
Perfect cubic cleavage
XPL Isotropic
δ None
Special properties
Salty taste
after Perkins, 366-367

Halite in Hand Sample

Subhedral halite
Rock salt from the Dead Sea, Israel
Halite casts in Tonoloway Formation limestone
Scanning electron micrograph of halite
Scanning electron micrograph of halite crystals on a grain of sand

Ragged halite crystal on a grain of sand from Satellite Beach, FL

Halite in Thin Section

Stay tuned for explorable images!

Halite, plane polars

Halite, crossed polars

Further Reading

Halite at webmineral.com
Halite at mindat.org