Gemological Characteristics and Genesis of Aventurescence in a Typical Sunstone Sample from Tanzania

doi:10.19657/j.geoscience.1000-8527.2025.009

Abstract

Abstract:

As a noteworthy member of the feldspar family, sunstone has garnered significant attention due to its distinctive aventurescence. This study extensively investigates the mineral composition and inclusion characteristics of a sunstone sourced from Tanzania through a combination of conventional gemological tests and advanced analytical techniques, including polarizing microscopy, X-ray fluorescence spectroscopy (XRF), laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), electron microprobe analysis (EPMA), X-ray powder diffraction (XRD), infrared spectroscopy (IR), and Raman spectroscopy. The findings reveal that the sunstone is classified as a potassium feldspar mineral, predominantly comprising microcline. Numerous inclusions exhibiting orange-red, green, and brown colors are identified as hematite, displaying a layered arrangement oriented in two mutually perpendicular directions, thereby producing a unique aventurescence. This research provides valuable insights into the mineralogical characteristics of sunstone and contributes to the broader understanding of its gemological properties.

Key words: sunstone, inclusion, feldspar group mineral, aventurescence, Tanzania

CLC Number:

YU Liyuan, LIU Yingxin. Gemological Characteristics and Genesis of Aventurescence in a Typical Sunstone Sample from Tanzania[J]. Geoscience, 2025, 39(01): 224-230.

Figures/Tables 13

References 17

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区域	SiO₂	Al₂O₃	K₂O	CaO	BaO	SrO	Fe₂O₃	Rb₂O	TiO₂	CuO	NiO	总计
a	62.06	22.27	14.62	0.35	0.32	0.07	0.05	0.03	-	0.01	-	99.78
b	62.07	21.81	15.11	0.28	0.35	0.07	0.05	0.03	0.02	0.01	0.01	99.81
c	60.83	21.64	16.31	-	0.49	0.11	0.07	0.03	0.01	0.02	0.01	99.52

区域	SiO₂	Al₂O₃	K₂O	CaO	BaO	SrO	Fe₂O₃	Rb₂O	TiO₂	CuO	NiO	总计
a	62.06	22.27	14.62	0.35	0.32	0.07	0.05	0.03	-	0.01	-	99.78
b	62.07	21.81	15.11	0.28	0.35	0.07	0.05	0.03	0.02	0.01	0.01	99.81
c	60.83	21.64	16.31	-	0.49	0.11	0.07	0.03	0.01	0.02	0.01	99.52

样品	SiO₂	Al₂O₃	K₂O	Na₂O	BaO	CaO	TiO₂	TFeO	MnO	Cr₂O₃	MgO	NiO	总计(%)
Sun-1	64.00	19.03	13.89	1.17	0.27	0.07	0	0.03	0.02	-	-	0.01	98.49
Sun-2	65.03	18.60	13.95	1.25	0.35	0.14	0.04	0	0.05	-	-	0.02	99.43
Sun-3	64.64	19.10	14.33	1.32	0.36	0.11	0	0.01	0.02	0.01	0.01	0	99.91
平均(%)	64.57	18.91	14.07	1.25	0.33	0.11	0.01	0.01	0.03	-	-	0.01	99.28
阳离子系数	2.984	1.030	0.830	0.112	0.006	0.006	-	-	0.001	-	-	-

样品	SiO₂	Al₂O₃	K₂O	Na₂O	BaO	CaO	TiO₂	TFeO	MnO	Cr₂O₃	MgO	NiO	总计(%)
Sun-1	64.00	19.03	13.89	1.17	0.27	0.07	0	0.03	0.02	-	-	0.01	98.49
Sun-2	65.03	18.60	13.95	1.25	0.35	0.14	0.04	0	0.05	-	-	0.02	99.43
Sun-3	64.64	19.10	14.33	1.32	0.36	0.11	0	0.01	0.02	0.01	0.01	0	99.91
平均(%)	64.57	18.91	14.07	1.25	0.33	0.11	0.01	0.01	0.03	-	-	0.01	99.28
阳离子系数	2.984	1.030	0.830	0.112	0.006	0.006	-	-	0.001	-	-	-

测点	Na₂O	MgO	Al₂O₃	SiO₂	P₂O₅	K₂O	CaO	TiO₂	FeO	总计
Point1	1.480	0.004	20.695	62.724	0.040	14.196	0.279	0.003	0.021	99.442
Point2	1.467	0.004	19.921	63.467	0.034	14.359	0.252	0.003	0.020	99.527