Feldspar

Feldspar (silicate, chemical formula Na(AlSi₃O₈), where Na can also be replaced by K) is one of the main constituents of the Earth’s crust. Feldspar can be characterised by:

 

• Relatively high Mohs hardness of 6
• Low electrical conductivity
• Easy to wet
• High inertness in various media.

 

And, depending on the grade:

 

• Low content of lamellar mica
• Low fine crystalline silica fraction (no labelling)
• Whiteness

 

Note when using feldspar: depending on the particle size distribution of certain products, they can be labelled STOT RE 2. For more detailed information, visit www.safesilica.eu.

Sibelco feldspar quarry in Cine (Turkey)

 

Basic properties

Property	Value	Unit
Moisture	< 0.5	[%]
Hardness (Mohs)	6 (6.5)	[-]
Refractive index	1.53	[-]
L.O.I.	0.5	[%]
Density	2.6	[kg/ dm3]

 

 

Product overview

Product	Grade	D50 [µm]	D97 [µm]	OA [g/ 100 g]	pH	L*
Feldspar	FF-20	6	n.d.	32	9.8
	FF-30	8	n.d.	28	9.7
	FF-60	19	n.d.	27	9.5
	FF-150	23	n.d.	24	9.4
	PG4	4	17	26	9.5	94.5
	PG W7	7	25	27	8.0	97.0
	PG W13	13	60	22	8.1	96.4
	PG W20	20	80	19	8.2	96.2

Production locations Feldspar

 

 

Application

Feldspar will provide:

 

• Abrasion resistance: due to its hardness of 6 on Mohs scale, feldspar will increase the coating’s resistance to wear.
• Chemical resistance: due to its inert nature, feldspar will provide good chemical resistance compared to conventional fillers.
• Brightness: being a filler with a high brightness, feldspar (Unispar PG W) contributes to the visibility of road marking paints.
• UV resistance: being insensitive to UV radiation, feldspar will reduce the coating’s degradation.

 

Advantage over quartz and cristobalite: several feldspar grades are free of labelling, and can therefore be used as an alternative when fine quartz or cristobalite grades are no longer allowed.