The Hunsrück Slate (German: Hunsrück-Schiefer) is a Lower Devonian lithostratigraphic unit, a type of rock strata, in the German regions of the Hunsrück and Taunus. It is a lagerstätte famous for exceptional preservation of a highly diverse fossil fauna assemblage.
The Emsian stratigraphy of the southern Rhenish Massif can be divided into two lithological units: the older slates of the Hunsrück-Schiefer and the younger sandstones of the Singhofener Schichten. Stratigraphically below the Hunsrück Slates is the (older) Taunus quartzite. All these metasedimentary rocks were originally deposited in the marine Rhenohercynian Basin, a back-arc basin south of the paleocontinent of Laurussia.
The Hunsrück Slate roughly comprises the Sauerthal-Schichten, Bornich-Schichten and Kaub-Schichten. These are 408–400 Mya old, making them part of the Latest Pragian to Early Emsian stages of the Devonian.
The Hunsrück slate was a source for Rhenish slate over several centuries. Archaeological finds in West Germany show that the slate was used in Roman times. The first documented case of mining in this area dates from the 14th century. The production continued with the Industrial Revolution at the end of the 1700s, but in 1846-49, the industry fell into crisis, resulting in poverty and misery in the mining areas.