The mineral uytenbogaardtite, Ag₃AuS₂, is a soft, greyish white sulfide mineral, occurring in hydrothermal Au-Ag-quartz veins. It occurs as tiny crystals, visible only with a microscope. It has a metallic luster and a hardness on the Mohs scale of 2 (gypsum).

Uytenbogaardtite
Uytenbogaardtite, from New Bullfrog Mine, Nye County, Nevada, United States of America
General
Category	Sulfide mineral
Formula (repeating unit)	Ag3AuS2
IMA symbol	Uyt[1]
Strunz classification	2.BA.40b
Crystal system	Trigonal
Crystal class	Ditrigonal pyramidal (3m) H-M symbol: (3m)
Space group	R3c
Identification
Formula mass	584.70 g/mol
Color	Greyish white
Crystal habit	Microscopic crystals
Fracture	Irregular
Tenacity	Malleable
Mohs scale hardness	2
Luster	Metallic
Diaphaneity	Opaque
Specific gravity	8.405
Pleochroism	Weak
References	[2][3][4][5][6]

It forms, together with petzite (Ag₃AuTe₂) and fischesserite (Ag₃AuSe₂) the uytenbogaardtite group. The type locality is Tambang Sawah, Bengkulu district, Sumatra island, Indonesia.

Common impurities in the uytenbogaardtite are copper, selenium, and tellurium.

It is named after the Dutch mineralogist Willem Uytenbogaardt (1918–2012), Professor of Geology, Technical University, Delft, The Netherlands, prominent ore microscopist.