A use of at least one mixed mineral organoclay rheology additive, which comprises or consists of a quaternary alkyl-ammonium salt treated mineral clay mixture prepared by i. forming an aqueous hormite clay slurry (a) ii. forming an aqueous smectite clay slurry (b) iii. combining the aqueous hormite clay slurry (a) with the aqueous smectite clay slurry (b) to form a combined clay slurry (c) iv. treating the combined clay slurry (c) with one or more quaternary alkyl-ammonium salts v. separating the thus produced quaternary alkyl-ammonium salt treated mineral clay mixture from the aqueous medium, in which the aqueous hormite clay slurry (a) being formed by (i.1) dispersing a fraction of one or more hormite clays selected from the group of sepiolites and palygorskites in an aqueous medium to form a dispersion, and wherein the hormite clay fraction employed contains less than 3.0 % by weight of Al 2 O 3, less than 1.0 % by weight of Fe 2 O 3, and less than 3.5 % by weight of the combination of Al 2 O 3 and Fe 2 O 3, and the aqueous smectite clay slurry (b) being formed by (ii. 1) dispersing a fraction of one or more smectite clays in an aqueous medium to form a dispersion, and in that the weight of the hormite clay content exceeds the weight of the smectite clay content in the combined clay slurry (c); and subjecting the dispersions formed in (i.1) and (ii.1) to high speed fluid shear in a dissolver before carrying out step iii. and/or after having carried out step iii; and wherein the fraction of one or more hormite clays employed in the formation of the aqueous hormite clay slurry (a) exhibit a methylene blue exchange capacity below 20 mmol methylene blue per 100 g of the one or more hormite clays in dry state, the methylene blue exchange capacity being determined as described in the experimental section on the part of an aqueous hormite clay slurry that passes a 100 mesh U.S. standard screen having 149 μm mesh openings, and the hormite clay slurry before passing the 100 mesh U.S. standard screen having a particle size distribution such that at least 90 % by weight of the hormite clay contained in the aqueous hormite clay slurry passes the 100 mesh U.S. standard screen and wherein the fraction of one or more hormite clays employed in the formation of the aqueous hormite clay slurry (a) has an integral breadth B defined according to formula B = net area of reflection / net height of reflection of the reflection with Miller indices of less than 0.800 scan units in an X-ray powder pattern recorded on an oriented glycolated sample of the hormite clay fraction, prepared by air-drying an aqueous slurry of the hormite clay having a solid content in the range of 2.0 to 0.5 % by weight and placing the air dried slurry in a glyclolation chamber under vacuum for a minimum of 12 hours, using Cu-K α1 -radiation, in a liquid composition. i. forming an aqueous hormite clay slurry (a) ii. forming an aqueous smectite clay slurry (b) iii. combining the aqueous hormite clay slurry (a) with the aqueous smectite clay slurry (b) to form a combined clay slurry (c) iv. treating the combined clay slurry (c) with one or more quaternary alkyl-ammonium salts v. separating the thus produced quaternary alkyl-ammonium salt treated mineral clay mixture from the aqueous medium, (i.1) dispersing a fraction of one or more hormite clays selected from the group of sepiolites and palygorskites in an aqueous medium to form a dispersion, and wherein the hormite clay fraction employed contains less than 3.0 % by weight of Al 2 O 3, less than 1.0 % by weight of Fe 2 O 3, and less than 3.5 % by weight of the combination of Al 2 O 3 and Fe 2 O 3, and the aqueous smectite clay slurry (b) being formed by (ii. 1) dispersing a fraction of one or more smectite clays in an aqueous medium to form a dispersion,