Halloysite is an industrial mineral that is part of the kaolinite group. Like kaolin, halloysite is essentially composed of alumina-silicates, however it has a hollow tubular crystal structure, which is markedly different from the booklet or platelet crystal structure of kaolin.

A typical chemical analysis is: 

• Loss on Ignition   13.8
• SiO_²      50.4
• Al_²O_³     35.5
• Fe_²O_³     .25
• TiO_²     .05
• CaO   Trace
• MgO   Trace
• K_²O   Trace
• Na_²O   Trace
  

GRIT.  . . . . .Less than 0.10 per cent on a 240 mesh BSS Screen for dispersed solution.
COLOUR. . . . . . . . Brightness typically 98.9 L* as measeured by a Minolta CR300 Colorimeter using D65 Light source..  Fired at 1280°C
pH OF AQUEOUS SLURRY AT 20 PER CENT SOLIDS. . . . 3.5 - 4.5
SPECIFIC GRAVITY . . . . . . . .2.55
FLUORIDE ION . . . . Less than 0.01% as F¯ (B.C.R.A.)
CATION EXCHANGE CAPACITY . . . . . . . . .Approximately 10 milli equivalents  100 gms of Clay
SURFACE AREA. . . . .Approximately 20 m²/gm
DISPERSIBILITY..........For ceramic applications the clay needs to be either ball milled or blunged under high shear.

" Every precaution is taken in production to ensure the clays conform to the above data but as the products are based on naturally occuring raw materials, minor variations may occur."