Crystal system: Not applicable Refractive index: Birefringence: Cleavage: Twinning: Colour in PPL: Pleochroism: Relief: Distinction: Occurrence: Distinct boundaries and pottery structure	Grog - Plain polarized light - Sangalan Tepe -Iran
	Piece of grog within a piece of grog - Plain polarised light - Godin Tepe - Iran

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