Caracterização mineralógica das associações de argilominerais em pegmatitos do estado do Rio de Janeiro com enfoque na identificação de depósitos de caulinita e/ou halloysita

Salgado-Campos, V. M. J.; Bertolino, L. C.; Silva, F. J. da; Mendes, J. C.

doi:10.1590/0366-69132020663802928

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Articles • Cerâmica 66 (380) • Oct-Dec 2020 • https://doi.org/10.1590/0366-69132020663802928 copiar

Caracterização mineralógica das associações de argilominerais em pegmatitos do estado do Rio de Janeiro com enfoque na identificação de depósitos de caulinita e/ou halloysita

Autoria SCIMAGO INSTITUTIONS RANKINGS

Resumo

Este estudo reporta a caracterização mineralógica de ocorrências de caulim no estado do Rio de Janeiro, Brasil, com enfoque na identificação de depósitos de caulinita e/ou halloysita. Amostras foram coletadas em 10 pegmatitos de dimensões variadas para estudos de difratometria de raios X, análise química por fluorescência de raios X e microscopia eletrônica de varredura. As ocorrências de caulim nos corpos pegmatíticos foram de origem intempérica, onde em alguns locais houve ocorrência de halloysita tubular. Dentro da estratigrafia do regolito, as amostras localizadas na zona de saprock apresentaram teores de caulinita e/ou halloysita entre 0 e 10,1%, enquanto aquelas localizadas no saprólito apresentaram maiores teores de caulinita entre 16,3% e 34,9%. A caulinita e/ou halloysita foram formadas a partir da alteração de plagioclásio e não de K-feldspato ou mica, estando a ocorrência de halloysita associada a locais de grau de intemperismo mais elevado.

Palavras-chave:
caulim; caulinita; halloysita; Rietveld; Rio de Janeiro

Table I Sampling sites in the Cantagalo-São Fidélis and Niterói-Rio Bonito areas.

Pegmatite	Number of samples	Area	Municipality	Latitude	Longitude	Elevation (m)
Córrego do Ouro (CA-3)	2	Cantagalo-São Fidélis	Cantagalo	-21.842	-42.217	332
Boa Sorte Superior (CA-2)	0*	Cantagalo-São Fidélis	Cantagalo	-21.863	-42.233	370
Esmério (CA-4)	2	Cantagalo-São Fidélis	Cantagalo	-21.875	-42.251	426
RB-1	2	Niterói-Rio Bonito	Rio Bonito	-22.708	-42.607	74
RB-2	2	Niterói-Rio Bonito	Rio Bonito	-22.703	-42.593	71
RB-3	2	Niterói-Rio Bonito	Rio Bonito	-22.754	-42.593	97
RB-4	1	Niterói-Rio Bonito	Rio Bonito	-22.700	-42.598	74
RB-5	2	Niterói-Rio Bonito	Rio Bonito	-22.719	-42.622	75
RB-6	1	Niterói-Rio Bonito	Rio Bonito	-22.786	-42.554	71
RB-7	1	Niterói-Rio Bonito	Rio Bonito	-22.702	-42.589	59
Calaboca-Rebentão (MA-1)	0*	Niterói-Rio Bonito	Maricá	-22.895	-42.946	41
SG-1	1	Niterói-Rio Bonito	São Gonçalo	-22.863	-42.987	63
SG-2	0*	Niterói-Rio Bonito	São Gonçalo	-22.863	-42.987	76
SG-3	0*	Niterói-Rio Bonito	São Gonçalo	-22.870	-42.987	96
SG-4	0*	Niterói-Rio Bonito	São Gonçalo	-22.870	-42.984	85

Table II Chemical compositions (wt%) used in the conversion of results from quantitative mineral analysis to chemical analysis.

Content	Mo	Ms	Kln/Hly	Qtz	Kfs	Pl
SiO₂	43.77	45.21	43.22	100.00	64.76	67.39
Al₂O₃	18.57	38.36	42.82	0.00	18.32	20.35
CaO	1.02	0.00	0.00	0.00	0.00	1.07
Na₂O	1.13	0.00	0.00	0.00	0.00	11.19
K₂O	0.00	11.81	0.00	0.00	16.92	0.00
LOI	36.09	4.07	13.96	0.00	0.00	0.00
F	0.00	0.55	0.00	0.00	0.00	0.00
Sum	100.58	100.00	100.00	100.00	100.00	100.00

Table III Classification by Pearson correlation coefficients.

ρ value (+ or -)	Interpretation
0.00 to 0.19	Very weak correlation
0.20 to 0.39	Weak correlation
0.40 to 0.69	Moderate correlation
0.70 to 0.89	Strong correlation
0.90 to 1.00	Very strong correlation

Table IV Results of quantitative mineral analysis of the bulk fractions obtained by the Rietveld method and its figures of merit and chemical analysis by XRF in oxides and calculated indexes.

	CA-3A	CA-3B	CA-4A	CA-4B	RB-1A	RB-1B	RB-2A	RB-2B	RB-3A	RB-3B	RB-4	RB-5A	RB-5B	RB-6	RB-7	SG-1C
Mineralogy (wt%)
Sm	0.0	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	3.1	0.0	7.2	0.0	0.0	0.0	0.0
Mi+Ill	4.5	3.1	1.0	4.5	3.9	13.0	45.3	46.2	8.5	46.9	1.5	7.7	9.5	22.9	41.4	16.0
Kln+Hly	0.0	0.0	4.0	4.5	6.4	1.6	16.3	6.6	1.7	0.0	34.9	18.5	17.2	23.9	33.3	10.1
Qtz	31.9	27.8	13.6	44.8	9.2	35.5	38.4	47.2	31.8	50.0	27.1	44.3	48.5	36.4	25.4	43.3
Kfs	2.6	7.1	1.2	6.0	20.8	23.9	0.0	0.0	2.8	0.0	36.6	22.3	24.8	16.8	0.0	24.7
Pl	60.9	61.9	80.2	40.0	59.7	26.0	0.0	0.0	55.3	0.0	0.0	0.0	0.0	0.0	0.0	5.8
Sum	99.9	100.0	100.0	99.8	100.0	100.0	100.0	100.0	100.1	100.0	100.1	100.0	100.0	100.0	100.1	99.9
Rietveld (wt%)
SiO₂	76.7	75.6	70.6	79.8	67.4	75.1	66.1	71.1	75.4	72.7	66.5	73.4	76.3	68.0	58.6	74.9
Al₂O₃	14.6	15.1	18.6	12.9	20.2	15.4	24.4	20.6	15.7	18.6	22.2	16.3	15.6	22.1	30.2	16.2
CaO	0.7	0.7	0.9	0.4	0.7	0.3	0.0	0.0	0.6	0.0	0.0	0.1	0.0	0.0	0.0	0.1
Na₂O	6.8	6.9	9.0	4.5	6.7	2.9	0.0	0.0	6.2	0.0	0.0	0.1	0.0	0.0	0.0	0.7
K₂O	1.0	1.6	0.3	1.6	4.0	5.6	5.4	5.5	1.5	5.6	6.4	4.7	5.3	5.6	4.9	6.1
LOI	0.2	0.2	0.6	0.8	1.1	0.8	4.1	2.8	0.6	3.0	4.9	5.5	2.8	4.3	6.3	2.1
Sum	99.99	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Chemistry (wt%)
SiO₂	70.80	69.70	63.80	75.10	64.50	73.60	60.40	70.80	72.30	71.20	63.00	67.40	70.90	67.70	57.00	71.50
Al₂O₃	18.20	18.70	24.10	16.60	22.20	15.60	26.40	16.00	17.30	18.10	25.90	23.30	20.50	21.90	30.10	19.40
Fe₂O₃	0.47	0.60	0.27	0.26	0.74	1.00	2.60	3.30	0.46	1.60	0.48	0.68	0.80	1.00	1.10	0.91
MnO	0.00	0.00	0.00	0.00	0.00	0.00	0.15	0.05	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
MgO	0.17	0.15	0.00	0.00	0.27	0.50	0.46	0.81	0.56	0.83	0.28	0.40	0.17	0.58	0.53	0.24
CaO	1.40	1.50	2.50	1.40	0.15	0.51	0.00	0.00	0.27	0.05	0.00	0.00	0.00	0.00	0.00	0.20
Na₂O	7.10	7.30	7.40	4.20	6.20	3.20	0.00	0.00	4.50	0.19	0.31	0.17	0.22	0.23	0.00	1.10
K₂O	1.00	1.20	0.51	1.10	3.40	4.10	2.20	2.30	1.40	2.60	4.70	2.60	4.00	2.70	2.00	3.50
TiO₂	0.00	0.00	0.00	0.00	0.05	0.15	0.15	0.83	0.05	0.51	0.00	0.19	0.05	0.10	0.43	0.00
P₂O₅	0.00	0.00	0.00	0.00	0.11	0.05	0.11	0.05	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
ZrO₂	0.00	0.00	0.00	0.00	0.00	0.00	0.13	0.05	0.00	0.00	0.00	0.00	0.00	0.00	0.17	0.00
LOI	0.65	0.74	1.20	1.20	2.40	1.20	7.20	6.00	3.20	5.10	5.40	5.20	3.40	5.70	8.80	2.80
Sum	99.79	99.89	99.78	99.86	100.02	99.91	99.80	100.19	100.04	100.18	100.07	99.94	100.04	99.91	100.13	99.65
Index
CIA	54.32	53.84	58.25	60.93	61.07	59.48	91.73	86.54	64.77	84.91	82.23	88.28	81.38	86.90	93.29	76.49
RE	0.0	0.1	4.6	8.2	7.0	2.5	26.5	12.5	2.5	6.2	47.8	46.1	33.4	37.6	44.6	17.8
Parameter
ρ	0.998	0.998	0.994	0.998	0.999	1.000	0.995	0.995	0.999	0.999	0.997	0.993	0.997	0.999	0.998	0.998
R²	0.995	0.995	0.988	0.996	0.998	0.999	0.990	0.990	0.997	0.997	0.994	0.985	0.993	0.998	0.996	0.996
Figure of merit*
GOF	2.32	2.44	2.23	1.96	2.06	2.20	2.63	2.62	2.31	2.95	2.44	3.07	2.33	2.13	3.82	2.85
Rexp	4.55	4.32	4.83	4.78	4.59	4.47	3.68	3.56	4.44	4.13	4.73	4.31	4.41	4.22	4.02	4.41
Rwp	10.57	10.55	10.75	9.36	9.44	9.82	9.67	9.34	10.27	12.19	11.56	13.24	10.25	9.01	15.36	12.54

Table V Results of quantitative mineral analysis (wt%) of the clay minerals based on the X-ray diffractograms of ethylene glycol-solvated, oriented slides (Biscaye’s method) 38.

Sample	Re	Mo	Ill	Kln/Hly
CA-3A	0	67	24	10
CA-3B	0	47	22	31
CA-4A	0	0	23	77
CA-4B	0	0	17	82
RB-1A	0	91	1	7
RB-1B	0	94	3	3
RB-2A	7	0	86	6
RB-2B	0	0	99	1
RB-3A	0	93	6	1
RB-3B	20	1	60	19
RB-4	0	0	12	88
RB-5A	0	93	3	3
RB-5B	0	1	40	59
RB-6	0	69	0	31
RB-7	0	0	74	26
SG-1C	0	8	22	70

Table VI Pearson correlation matrix between the chemical index of alteration (CIA) and the results of quantitative mineral and chemical analyses.

	CIA	Sm	Mi+Ill	Kln+Hly	Qtz	Kfs	Pl	Fs	SiO₂	Al₂O₃	Fe₂O₃	MnO	MgO	CaO	Na₂O	K₂O	TiO₂	P₂O₅	ZrO₂
CIA
Sm	0.32
Mi+Ill	0.70	0.04
Kln+Hly	0.70	0.05	0.16
Qtz	0.45	0.34	0.42	-0.05
Kfs	0.05	0.11	-0.49	0.40	-0.01
Pl	-0.91	-0.29	-0.62	-0.63	-0.65	-0.28
Fs	-0.92	-0.30	-0.83	-0.49	-0.68	0.12	0.92
SiO₂	-0.45	0.03	-0.26	-0.67	0.53	0.07	0.17	0.20
Al₂O₃	0.51	0.07	0.15	0.78	-0.42	0.07	-0.26	-0.24	-0.95
Fe₂O₃	0.57	-0.03	0.85	0.03	0.40	-0.35	-0.53	-0.68	-0.14	-0.03
MnO	0.39	-0.12	0.56	0.08	0.17	-0.34	-0.28	-0.42	-0.35	0.24	0.72
MgO	0.59	0.22	0.78	0.09	0.37	-0.23	-0.56	-0.67	-0.03	-0.09	0.69	0.24
CaO	-0.76	-0.22	-0.51	-0.51	-0.39	-0.34	0.81	0.70	0.16	-0.19	-0.47	-0.22	-0.67
Na₂O	-0.94	-0.29	-0.64	-0.64	-0.62	-0.23	0.98	0.93	0.20	-0.29	-0.53	-0.30	-0.59	0.82
K₂O	0.37	0.04	0.02	0.45	0.17	0.83	-0.60	-0.27	-0.03	0.09	0.11	-0.06	0.22	-0.69	-0.56
TiO₂	0.54	0.19	0.81	0.04	0.38	-0.41	-0.49	-0.67	-0.07	-0.07	0.79	0.24	0.79	-0.41	-0.51	0.02
P₂O₅	0.05	-0.19	0.28	-0.10	-0.25	-0.04	0.00	-0.01	-0.28	0.10	0.52	0.66	0.18	-0.26	0.00	0.21	0.15
ZrO₂	0.55	-0.15	0.67	0.46	-0.05	-0.44	-0.37	-0.55	-0.70	0.62	0.51	0.58	0.30	-0.29	-0.39	-0.12	0.43	0.32
LOI	0.94	0.20	0.74	0.73	0.22	-0.10	-0.77	-0.84	-0.62	0.62	0.57	0.43	0.64	-0.72	-0.82	0.24	0.58	0.14	0.72

Table VII Comparison between the results of quantitative mineral analyses of the three most interesting kaolin occurrences from Rio de Janeiro, two giant sedimentary kaolin deposits at the North Brazilian region, and the Campo Alegre kaolin deposit in Santa Catarina, Brazil.

Mineralogy	Sedimentary deposits ²⁸28 I.R. Wilson, H. Souza Santos, P. Souza Santos, Clay Miner. 41, 3 (2006) 697.			Campo Alegre ²⁷27 M.T.G. De Oliveira, S.M.A. Furtado, M.L.L. Formoso, R.A. Eggleton, N. Dani, An. Acad. Bras. Ciênc. 79, 4 (2007) 665.			This study
Mineralogy	Capim River	Jari River	Ox1	Inc2a	Ce2m	RB-4	RB-6	RB-7
Mica+illite	0.0	0.0	6.4	20.9	48.0	1.5	22.9	41.4
Kaolinite+halloysite	100.0	100.0	35.0	65.8	44.3	34.9	23.9	33.3
Gibbsite	0.0	0.0	1.5	0.0	0.0	0.0	0.0	0.0
Quartz	0.0	0.0	4.5	13.2	7.7	27.1	36.4	25.4
K-feldspar	0.0	0.0	52.5	0.0	0.0	36.6	16.8	0.0
Sum	100.0	100.0	99.9	99.9	100.0	100.1	100.0	100.1

Associação Brasileira de Cerâmica Av. Prof. Almeida Prado, 532 - IPT - Prédio 36 - 2º Andar - Sala 03 , Cidade Universitária - 05508-901 - São Paulo/SP -Brazil, Tel./Fax: +55 (11) 3768-7101 / +55 (11) 3768-4284 - São Paulo - SP - Brazil
E-mail: ceram.abc@gmail.com

Acompanhe os números deste periódico no seu leitor de RSS

[1] * victorsalgadocampos@hotmail.com