Geological and Physicochemical Study of the Alluvial Clay of the Monoun Plain (West Cameroon) As Raw Materials for Ceramic Product

Clay Science 22, 29–37 (2018)

–Paper–

GEOLOGICAL AND PHYSICOCHEMICAL STUDY OF THE ALLUVIAL CLAY OF THE MONOUN PLAIN (WEST CAMEROON) AS RAW MATERIALS FOR CERAMIC PRODUCT

a a, b Isaac Yannick Bomeni , Armand Sylvain Ludovic Wouatong *, François Ngapgue , c d Véronique Kamgang Kabeyene , and Nathalie Fagel

a Department of Earth Sciences, University of Dschang, P.O. Box 67 Dschang Cameroon b Department of Civil Engineering, Fotso Victor Institute of Technology, P.O. Box 134 Bandjoun Cameroon c Department of Earth Science, Higher Teacher Training College, P.O Box 47 Yaoundé Cameroon d Department of Geology, University of Liege, 4000, Liege Belgium

(Received August 30, 2017. Accepted March 26, 2018)

ABSTRACT

This study reports the geological and physicochemical characterization of Monoun plain alluvial clays. The field was profiled using an auger corer in three localities (Njimbet, Bangourain, Ngwenfon). The present results reveal good indices of alluvial clay deposits with thicknesses ranging from 0 to 620 centimeters and are made up of various facies. The clay samples were collected from six representative profiles at different localities and they indicated silty clay texture except NJB1_2 and BGR2_2, i.e., a sandy clay texture. In all sample, quartz, kaolinite, goethite, illite and chlorite are the major minerals, while gibbsite, hematite, anatase, and K-feldspar are the minor minerals. Chemical analysis revealed the silico–aluminous character of samples with various

iron products (1%

Key words: alluvial clays, geology, mineralogy, physicochemical, ceramic raw material

INTRODUCTION (Künhel, 1990; Murray, 2000). Cameroon products some important clay deposits (Nguetnkam, 2004) all over the country. Clays and clay minerals, the most important materials Since three decades, several investigations on clays and clay used by the manufacturing and environmental industries materials have been performed in different localities (Fig- (Nora, 1999), have been exploited since the Stone Age. ure 1) to obtain the data base for their potential applications. However, an utilization of clay and clay minerals depends For instance, in the central region, alluvial clay from Nanga on their mineralogy, physico-chemical properties and abun- Eboko and Ebebda can be used in firing bricks on an addition dance (Wilson, 2004). Particularly, the clay in SiO2 and of sand to it (Nzeukou et al., 2013). Same characteristics are Al2O3 are used as ceramics (Bagdad et al., 2016; El Yak- also observed on clays from Ngog-Lituba localty (Figure 1), oubi et al., 2006), rubber (Njopwouo, 1984), paint (Zhang i.e., they are suitable for the production of earthenware at et al., 2010), and geochemical barriers (Murray, 2000; Saikia temperatures lower than 950°C (Ndjigui et al., 2016). The et al., 2003). Because of their wide industrial applications, hydromorphic clays from Yaounde area exhibit a high plastic clays are important for the social economic development index which allow their utilization for pottery and brick mak- ing (Ngon Ngon et al., 2009), and the clays from Ozom I are useful for manufacture tiles by adding 47 to 67% of sand and * Corresponding author: Wouatong Armand Sylvain Ludovic, De- flexural agent (Mamba Mpelé, 1993). In the North-West re- partment of Earth Sciences, University of Dschang, P.O. Box 67 gion, Yongue et al. (2016) show that alluvial clays from Ndop Dschang Cameroon. e-mail: [email protected] plain have varied colours like brown, grey and yellowish doi: 10.11362/jcssjclayscience.22.2_29 brown. These clays are able to use for production of roofing 30 I. Y. Bomeni et al.

Fig. 1. Map showing areas where alluvial clays have been studied Fig. 2. Geological map of the study area; modified from Dumort in Cameroon. (1968) and Moundi et al. (2007); the black stars indicate the sampling point. tiles, light weight blocks and hollow bricks at a temperature range from 900 to 1100°C. In the North region, the Ngaye GEOGRAPHICAL AND GEOLOGICAL SETTING alluvial clastic clays are useful for the fabrication of bricks (commons and perforated) by an addition of fluxing agent to The study area locates (Figure 2) on the western flank of improve the mechanical performance of the ceramic products Mbam massif (latitude 5°49′ to 6°20′N and longitude 10°36′ (Djenabou et al., 2014). In the Far-North region, alluvial clays to 10 °45′E) and covers a total area of 145 km2. The Mbam from Maroua are used in burnt brick when mixed with other massif is characterized by an elliptical shape with numerous clays, followed by the addition of a flexural agent (Tsozué valleys (Dumort, 1968). It is essentially made of volcanic et al., 2017). In West region, particularly Noun division, al- rocks covering the gneissic basement. The basalt is made luvial clays have been already identified at Marom valley, up of variable proportions of plagioclase, pyroxenes and ac- Njindare valley, Koutaba plain and Monoun plain, respec- cessory opaque minerals (Moundi, 2004). The study area is tively (Nkalih, 2016). In koutaba plain, kaolinite (27–62%) covered by basalt, granite, rhyolite and alluvium from the are major minerals associated with illite (2–13%), smectite weathering of different rocks on the massif. (1–25%) and quartz (11–48%). This mineralogical composition of alluvial clays from Koutaba renders it inappropriate MATERIALS AND METHODS in ceramic products due to the high smectite contents (up to 20%) and some treatments are needed like addition of quartz Alluvial samples or sand before any ceramic application (Nkalih, 2016). So far Seventeen species of alluvial clays were collected from six in, just a superficial investigation was carried out in above representative profiles (0–620 cm) using hand auger corer. mentioned localities. Therefore, the alluvial clays around The corings were made according a 2 km grid in the localities Monoun plain will be specifically subjected to geological of Njimbet, Bangourain and Ngwenfon (Figure 2). Each pro- and physicochemical study to determine its suitability as raw file was described and divided based on texture and colour. A materials for the ceramic industry. The obtained results com- sample was taken in each level of the profile. pared to previous literatures about other alluvial clays along the country and Europe. Mineralogical analysis X-ray diffraction (XRD) was performed for mineralogical analysis. The XRD patterns were obtained by using a Bruker Geological and physicochemical study of the alluvial clay of the monoun plain (west cameroon) as raw materials for ceramic product 31

D8 Advance diffractometer (Department of Geology, AGEs, Physical analysis University of Liege, Belgium) at 40 kV and 25 mA, providing The particle size was determined by wet sieving for frac- a CuKα1 radiation (λ=1.5406 Å). tion ≥80 µm and sedimentry for fraction ≤80 µm according For the analysis of the total disoriented powder, the samples to AFNOR (1992). were first crushed in an agate mortar to obtain particle size Plastic limit was performed on fractions<400 µm. Atter- fraction lower than 150 µm, then dried at 105°C for 24 h. The berg limits was used in order to define the limits of consisten- powder was placed on a sample carrier. The measurements cy between the solid and the plastic state, (plastic limit: WP) were carried out in the 2θ range of 2° to 40° with an angular and the plastic state to the liquid state (liquid limit: WL). The step of 0.01°/s. The relative abundance of minerals has been interval between the plastic limit and liquid limit defines the estimated from the height of diagnostic peak multiplied by plastic index (IP). The plastic limit test was carried out accord- correction factors defined by Cook et al. (1975) and Boski ing to the AFNOR (1993) in the laboratory of MIPROMALO et al. (1998). (Yaoundé-Cameroon). For the analysis of oriented aggregates, samples were placed in solution with water and sieved at 63 µm. The clay fraction RESULTS AND DISCUSSION (< 2 µm) was isolated after a settling time according to Stoke’s law and placed on the slide glass (Moore et al., 1989). Three Description of profiles X-ray patterns were recorded for each sample: air-dried (N), Monoun plain is covered by alluvium and the representa- ethylene-glycol solvated for 24 h (EG), and heated at 500°C tive profiles from Bangourain (BGR1&BGR2), Ngwenfon for 4 h (H). Semi-quantitative estimation of clay minerals was (NGW1 & NGW2) and Njimbet (NJB1 & NJB2) are domi- based on the height of specific reflections measured by the EG nated by silty clay with different colours (Figure 3). condition, multiplied by corrective factors (Thorez, 1976) as Profile BGR1 (E10 °41′40″; N5°52′40″) comprise of five lay- reported in Fagel et al. (2003). ers (Figure 3a). From top to the bottom, the first layer (10 cm)

corresponds to the top soil (a1) and contains many rootlets. Infrared analysis The second layer (150 cm) is pale brown (a2: 10YR6/3) The infrared spectroscopy was performed with a resolution with silty clay texture. The third layer (150 cm) is black −1 −1 of 4 cm between 4000 and 400 cm wave number with a (a3: 10YR2/1) and has a silty clay texture. The fourth layer Bruker Nicolet Nexus at the mineralogical laboratory in the (190 cm) is gray (a4:10YR6/1) and with a silty clay texture. The University of Liege, Belgium. The powdered sample (50 mg) fifth layer is reddish brown (a5: 5YR5/4) with a thickness of was diluted in 180 mg of KBr and pressed to form a pellet. The more than (130 cm). spectrum of pellet was recorded by accumulating 200 scans Profile BGR2 (620 cm) with coordinates (E10°38′40″; at a 1 cm−1. N5°53′40″) is composed of five layers, we observed three silty clay layers and one sandy clay texture. The first layer (20 cm)

Chemical analysis corresponds to the top soil (a1) and contains rootlets. The Chemical analysis was performed by the X-ray fluores- second layer (130 cm) is yellowish brown (a6: 10YR5/6) and cence spectrometer at the petrology laboratory of the Univer- has a silty clay texture. The third layer (70 cm) is light gray sity of Liege. The sample (0.34 mg) calcified at 1000°C was (b1: 10YR7/2) and has a sandy clay texture. The fourth layer mixed with KBr (3.74 mg), BrLi (0.0002 mg) and fired to form (130 cm) is gray (a4: 10YR6/1). The fifth layer (270 cm) is black pellets. The spectrum of major oxides in each sample was (a3: 10YR2/1). recorded by X-ray fluorescence spectrometer. Profile NGW1 (520 cm) has as coordinates E10°39′42″; N5°56′40″ that comprises five layers (Figure 3c) with the silty

Fig. 3. Description of proﬁle: a1- top soil; a2- pale brown silty clay; a3- black silty clay; a4- gray silty clay; a5- reddish brown silty clay; a6- yellowish brown silty clay; a7- brown silty clay; a8- grayish brown silty clay; a9- light olive brown silty clay; a10- light black; b1- light gray sandy clay; b2- dark gray sandy clay. 32 I. Y. Bomeni et al.

Fig. 4. XRD patterns of samples (a): Bulk XRD pattern. (b): Clay XRD pattern. N: Air dried condition; EG: glycolate condition; H: heat condition.

Table 1. Bulk data from disoriented powder and clay (Ф<2 µm) fraction from oriented aggregate. Bulk mineralogy (Powder) Clay mineralogy (θ< 2 µm) Quartz Total clay K-feldspar Anatase Goethite Hematite Gibbsite Kaolinite Illite Chlorite Corrective factor of each mineral 11 20 4.30 0.73 7 3.33 0.95 0.7 1.00 0.34 Cook et al. Boski et al. Thorez, 1976 in Fagel et al. Locality Id_sample Cook et al. 1975 1975 1998 2003 Bangourain BGR1_1 21 51 2 1 14 0 9 75 6 19 BGR1_2 21 51 2 1 14 0 9 75 6 19 BGR1_3 11 48 4 2 22 5 7 80 8 12 BGR1_4 13 31 13 1 20 3 1 89 0 11 BGR2_1 26 35 7 1 27 3 0 74 14 12 BGR2_2 23 46 7 2 23 0 0 82 11 7 BGR2_3 16 42 7 2 27 6 1 77 11 12 BGR2_4 16 15 41 1 13 2 0 80 13 7 Ngwenfon NGW1_1 23 52 6 2 14 0 0 77 15 8 NGW1_2 20 55 9 2 13 0 1 69 20 11 NGW1_3 30 41 6 1 19 0 1 80 11 9 NGW1_4 25 42 10 1 20 1 0 80 13 6 NGW2_1 34 39 6 1 18 1 1 Njimbet NJB1_1 22 37 13 1 25 2 0 79 11 10 NJB1_2 26 43 12 1 16 1 0 77 6 17 NJB2_1 20 54 5 1 16 2 1 90 4 5 NJB2_2 21 50 10 1 16 0 0 56 22 22 clay texture except from the first layer. From top to bottom, layers (Figure 3e). The first layer (120 cm) is polychrome, the first layer (30 cm) is the top soil (a1). The second layer contains many rootlets and corresponds to the top soil. The (320 cm) is brown (a7: 10YR5/3). The third layer (30 cm) is second layer (80 cm) is gray (a4: 10YR6/1). The third layer gray (a4: 10YR6/1). The fourth layer (40 cm) is light yellow- (120 cm) has a dark gray color (b2: 10YR4/1) with a sandy clay ish brown (a6: 10YR5/6). The fifth layer (100 cm) is black (a3: texture. 10YR2/1). The profile NJB2 (E10°39′0″; N5°51′40″) is composed of Profile NGW2 (E10 °40′31″; N5°50′40″) is composed of two three layers (Figure 3f). From top to bottom, we observed top layers (Figure 3d). The first layer (30 cm) is the top soil (a1) soil (100 cm) with many rootlets in the first twenty centime- and contains rootlets. The color of the top soil is varied and ters. The colour is varied and ranges from reddish to brown. ranges from reddish and brownish. The second layer (490 cm) The second layer (80 cm) is silty clay and light olive brown (a9: is grayish brown (a8: 10YR5/2). 2.5YR5/3). The third layer is silty clay, light black color (a10: Profile NJB1 (E10 °40′31″; N5°50′40″) is made up of three 2.5Y2.5/1) and the thickness is more than 220 cm. Geological and physicochemical study of the alluvial clay of the monoun plain (west cameroon) as raw materials for ceramic product 33

These auger profiles from Monoun plain are similar to that measured as shown in Figure 4. Bulk mineralogical composi- from Nanga Eboko and Ebebda (Nzeukou, 2014) in terms tion is constituted by quartz (11–34%), K-feldspar (2–41%), of varying colors of the facies. However, their textures are anatase (1–2%), goethite (13–27%), hematite (0–6%) and different: the sandy clay layers, alternated from the profile gibbsite (0–9%). Clayey minerals are consisted of kaolinite on Monoun, are not presented in Nanga Eboko and Ebebda (56–90%), illite (0–22%) and chlorite (5–22%) (Table 1). The alluvial clays. These phenomena are due to their origin and presence of illite and chlorite in the presented clays may pro- the condition of deposition. Alluvial clays from Nanga Eboko mote the glassy phase responsible for the densification of the and Ebebda are derived from the weathering of gneiss and final product (Nzeukou, 2014). are carry out on a long distance by the Sanaga River. How- The similar mineralogical composition is also observed in ever, the alluvial clays from Monoun plain is a mixture of the alluvial clay from Ndop plain (Yongue et al., 2016); Nanga weathered basalt, granite and rhyolite (Figure 2) which are Eboko and Ebebda (Nzeukou et al., 2013). In contrast, the weakly transported by river and runoff. mineralogical composition of clays from Ngwenfon, Njimbet and some samples from Bangourain are close to those from Mineralogy analysis Bavaria (Klradorf) area from Germany, one of European clay, For estimation of mineralogy composition, XRD patterns (Figure 5) which are used for bricks and potteries.

Infrared (IR) analysis The IR spectra of alluvial clays from Monoun plain conﬁrms the presence of kaolinite, illite, quartz and gibbsite (Figure 6). The absorption peak between 3700 cm−1 and 3600 cm−1, i.e., 3741 cm−1, 3687 cm−1, 3646 cm−1 and 3633 cm−1 in all samples excepted NGW1_1 and BGR2_3 attests the presence of kaolinite (Sdiri et al., 2010; Hammami-Ben Zaied et al., 2015). The absorption at 3633 cm−1 (BGR1_1, BGR1_3, BGR1_4, BGR2_1, BGR2_2) and 740 cm−1 indicates the presence of illite (Van Olphen and Fripiat, 1979). There are peaks between 1200 cm−1 and 900 cm−1 (e.g., 1041, 1012, and 916 cm−1) for all samples because of the stretching vibration of Si–O that conﬁrms the presence of quartz. The bands at 3525 cm−1 and 3430 cm−1 on BGR1_3, BGR1_4, BGR2_2, NJB2_2 and NJB1_2 indicate the presence of gibbsite (Brindley et al., 1986; Shroeder, 2002). The bands at 520 cm−1 and 466 cm- 1 correspond to the Fig. 5. Comparison of alluvial clays from Bangourain, Ngwenfon stretching vibration of Si–O–Al and Si–O–Mg, respec- and Njimbet, with a few Cameroonian and European commer- tively (Van der Marel and Beutelspacher, 1976; Velde and −1 −1 cial clays in ternary diagram of Fiori et al. (1989). Meunier, 2008). The peaks at 3430 cm and at 1623 cm or

Fig. 6. IR spectra of alluvial clays from Monoun plain. 34 I. Y. Bomeni et al. 1.4 0.0 0.6 0.6 0.0 0.2 0.0 0.1 2.5 2.5 37.5 39.7 55.6 16.7 53.0 65.0 12.0 22.6 22.8 NJB2_2 9.3 1.2 3.5 0.0 0.3 0.2 0.0 0.2 2.2 2.2 47.0 67.4 16.1 56.2 12.1 12.4 20.2 20.0 66.0 NJB2_1 / / / 1.5 1.3 1.3 1.3 5.2 0.0 0.0 0.1 0.1 6.3 2.6 11.5 57.0 79.5 12.4 22.0 NJB1_2 9.5 1.7 0.0 0.1 0.3 0.0 0.1 2.1 2.5 2.7 11.4 37.3 19.6 71.0 39.0 43.1 23.5 32.0 48.2 NJB1_1 1.8 1.2 1.2 0.1 0.0 0.3 0.0 0.1 6.9 2.4 47.9 27.0 35.8 69.0 13.5 43.8 20.4 26.4 42.0 NGW2_1 1.3 3.0 0.0 0.8 0.0 0.2 0.0 0.2 2.2 2.8 51.6 39.0 49.0 35.7 16.9 43.6 23.1 20.8 88.0 NGW1_4 1.1 1.1 0.1 0.0 0.3 0.3 0.2 2.1 2.7 21.0 19.8 14.1 15.1 63.0 25.1 34.0 28.0 40.7 44.2 NGW1_3 1.5 1.9 3.3 0.0 0.6 0.6 0.0 0.2 0.0 0.2 17.8 37.0 35.0 45.4 63.0 30.2 32.0 30.0 28.0 NGW1_2 9.6 1.7 1.7 0.0 0.1 0.3 0.0 0.1 2.1 2.6 39.0 35.7 43.6 43.0 12.5 20.8 48.7 82.0 22.7 NGW1_1 1.1 1.1 1.1 0.0 0.0 0.2 0.3 2.4 2.4 2.1 15.5 25.0 23.0 58.0 30.9 54.5 22.9 22.6 44.4 BGR2_4 1.2 1.2 1.1 0.1 0.0 0.3 0.1 8.0 2.0 2.4 14.0 13.6 30.9 50.0 36.0 24.6 48.4 22.6 44.4 BGR2_3 1.7 1.9 1.7 0.0 0.0 0.1 0.0 0.2 2.7 2.9 21.6 59.1 39.1 35.1 10.8 25.9 25.0 23.0 58.0 BGR2_2 9.3 1.2 1.7 3.5 0.0 0.3 0.2 0.2 2.2 2.2 17.8 57.4 14.0 16.1 23.1 50.0 56.2 12.1 36.0 BGR2_1 Table Table 2. Physicochemical composition alluvial of from clays Monoun plain. 1.3 5.8 0.0 0.1 0.1 0.0 0.1 0.0 2.0 2.0 11.0 41.4 14.0 35.0 16.2 33.0 42.8 42.7 46.0 BGR1_4 1.2 1.3 0.0 0.1 0.1 0.0 0.1 0.9 0.0 2.2 49.0 35.6 29.6 29.0 16.5 63.0 20.6 34.0 44.0 BGR1_3 1.8 1.7 3.4 0.0 0.3 0.5 0.2 0.4 0.1 6.5 17.7 47.7 21.1 29.0 10.6 63.0 30.7 34.0 60.6 BGR1_2 1.7 0.0 0.5 0.5 0.0 0.2 0.4 0.1 4.5 2.3 47.7 21.1 49.0 14.4 29.0 63.0 30.7 34.0 28.5 BGR1_1 3 O 2 /Al 2 3 3 5 2 2 O O Id_sample O 2 O 2 2 O 2 2 TiO Fe MnO Clay MgO Silt P Al LOI (%) Plastic index (%) Sand Gravel K Ratio SiO CaO SiO Liquid limit (%) Plastic limit (%) Na Geological and physicochemical study of the alluvial clay of the monoun plain (west cameroon) as raw materials for ceramic product 35

1612 cm−1 in all samples excepted NGW2_1 and NGW1_3 ranges from 11.0–29.0% at Bangourain, 12.0–32.0% at Njim- correspond to the absorption of the water contents (OH), i.e., bet and 32.0–49.0% at Ngwenfon, respectively. The plastic the presence of hydrated phyllosilicates (Madejova, 2003). index value of the present clays (11.0%) is higher than the lowest limit for utilization as ceramic application (10.0%; Physical analysis Abajo, 2000). The diagram of Marsigli and Dondi (1997) Particle size distribution and plastic index are important for evaluation of extrusion behavior (Figure 8) shows that parameters for evaluation of the utilization of clays as ce- these clay samples can be used for manufacture for bricks ramic building bricks (Dondi et al., 1998). It is worth noting (BGR1_4, BGR2_3, NJB2_2) or pottery. that, the alluvial clays presented here show similar grain size According to their mineralogy, grain size and plastic index distribution and wide spread (Table 2), with highly varying i.e., the main important parameters controlling the quality of a abundance of sand (19.6–79.5%), silt (12.4–67.4%) and clay ceramic product, of most raw clays from Monoun plain fit the (1.5–49.0%) fractions, associated with a low contribution of requested criteria to produce ceramics. gravel (0.0–6.3%). According to the literature of Winkler (1954), this kind of distribution is enabled to use these clays Chemical analysis for vertically perforated bricks, hollow products, roofing tiles Chemical properties of clays presented here (Table 2) and masonry bricks (Figure 7). As an exception, two samples is correlated to their mineralogical composition. The bulk from Njimbet (NJB1_2 and NJB2_1) are out of order for their chemical composition of the samples was generally consid- utilization as ceramic application fields (Figure 7). ered as a starting point to test for the fusibility of clays for The plastic index of the clays presented here (Table 2) ceramics bodies (Dondi et al., 1998). The amount of silica

(42.8%

ratio of alkali and alkaline earth oxides (K2O, Na2O, MgO and CaO) is low (< 3%), i.e., it seems that the clays presented here need ﬂuxing elements to increase their fusibility at low temperature. The loss of ignition (LOI) ranges from 9.3% (BGR2_1) to 17.8% (NGW1_2). According to Baccour et al. (2009); Milheiro et al. (2005); LOI value is related to the degree of deshydroxylation of the clayey minerals and to the degree of oxidation/decomposition of hydroxides of organic matter. Figure 9 shows the evaluation of the potential application of alluvial clays from Monoun plain as the ceramic products inside the ternary diagrams of Fiori and Fabbri (1985) and Fiori et al. (1989). The most samples (BGR1_1, BGR1_2, BGR1_4, BGR2_1, BGR2_3, NGW1_1, NGW1_3, NGW1_4, NGW2_1, NJB1_1, NJB1_2 and NJB2_1) belong to the group

of red stoneware tile (Fe2O3>4%) (Figure 9A), cottoforte tile Fig. 7. Ternary diagram from Winkler (1954). I: Common bricks; and majolica tile deﬁned from Italian ceramics (Figure 9 B). II: vertically perforated bricks; III: rooﬁng tiles and masonry Hereafter, our chemical datas are compared with available bricks; IV: hollow bricks. datas of alluvial Cameroon clays potentially used in ceramic

Fig. 8. Evaluation of extrusion behavior of alluvial clays from Monoun plain in Marsigli and Dondi (1997) diagram. 36 I. Y. Bomeni et al.

Fig. 9. Evaluation of the suitability of raw material base on empirical diagrams and comparison with a local ceramic used. (A) Ternary diagram of Fiori and Fabbri (1985). a: Red stoneware tile; b, b′, b″: white stoneware tile; (1) Ndop alluvial clays (North west Cameroon); (2) Ngaye alluvial clays (north Cameroon); (3) Nanga Eboko and Ebebda alluvial clays (center Cameroon); (4) Maroua alluvial clays (far North Cameroon); (B) Ternary diagram of Fiori et al. (1989). a: White stoneware; b: red stoneware; c: cottoforte; d: majolica. manufactures such as clays from Nanga Eboko and Ebebda joel from the “Laboratoire Argiles, Géochimie et Environne- (Nzeukou et al., 2013) for central Cameroon, from Ndop plain ments Sédimentaires (AGEs),” University of Liège, Belgium (Yongue et al., 2016) for North west Cameroon, from Ngaye for the mineralogical analyses. (Djenabou et al., 2014) and Maroua (Tsozué et al., 2017) for REFERENCES the Northern and Far North territories. 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