The new mineral argentopearceite (IMA2020-049) was found at the mine dump of the abandoned Lehnschafter mine, Mikulov–Hrob district (holotype), and later at museum samples (cotypes) from the Moldava fluorite deposit, both in the Krušné hory Mountains, Czech Republic. Argentopearceite is associated with proustite in quartz gangue (Mikulov) or acanthite and proustite in fluorite gangue (Moldava). The new mineral occurs as tabular (pseudo)hexagonal crystals up to 0.8 mm (Mikulov) and 3 mm (Moldava), and as groups and aggregates up to 1 cm. Argentopearceite from Mikulov is steel grey to black. Mohs hardness is ca. 3; the calculated density is 6.29 g.cm–3. In reflected light, argentopearceite is grey with a greenish shade. Bireflectance was not observed and pleochroism is very weak. Anisotropy under crossed polars is moderate with weak greenish and green–blue tints. Internal reflections were not observed. Reflectance values of argentopearceite in air (Rmin/Rmax, %) are: 27.3/30.0 at 470 nm, 26.6/29.3 at 546 nm, 26.2/28.8 at 589 nm, and 25.9/28.1 at 650 nm). The empirical formula for argentopearceite, based on electron-microprobe analyses (n = 15), is (Ag15.95Cd0.02)Σ15.97(As1.82Sb0.11)Σ1.93(S11.03Cl0.05Te0.01)Σ11.09. The ideal formula is Ag16As2S11, which requires (in wt.%) Ag 77.45, As 6.72 and S 15.83, total of 100.00. Argentopearceite is trigonal, P321, a = 14.8583(5), c = 12.3038(15) Å, with V = 2352.38(15) Å3 and Z = 4. Its crystal structure was refined by single-crystal X-ray diffraction data to a final R1 = 0.0773 on the basis of 6594 unique reflections with Fo > 3σ(F) and 242 refined parameters. The structure of argentopearceite mostly conforms to the general architecture of the As-dominant members of the pearceite–polybasite family of minerals.