Not everyone can convincingly compare a soil type to a classic French dessert, but Thierry Fritsch sees the sweetness in schist.\u00a0\r\n\r\n\r\n\r\nComprised of flaky layers of rocks and minerals, schist is \u201csort of a mille-feuille baked at high pressure in the depths of the earth\u2019s crust,\u201d says Fritsch, head oenologist and chief wine educator for Conseil Interprofessionnel des Vins d\u2019Alsace, a wine organization in Alsace, France.\r\n\r\n\r\n\r\nLike slate, schist is a metamorphic soil, meaning it formed when an intense bout of heat and pressure transformed one type of rock into another. Its fine-grained, crystalline character has pluses and minuses for winemakers.\u00a0\r\n\r\n\r\n\r\n\r\nSchist is \u201cresistant to weathering and erosion, and often produces very prominent terroirs,\u201d says Jordi Vidal, wine director for ThinkFoodGroup.\u00a0\r\n\r\n\r\n\r\nIt also retains heat well and has good drainage. These characteristics are useful for growers in hilly Alsace or those cultivating indigenous Carignan and Garnacha grapes in mountainous Priorat, Spain.\u00a0\r\n\r\n\r\n\r\n\u201cBoth these grape varietals need plenty of sunshine and heat to thrive, and the steep, mainly schist soils of Priorat are excellent for retaining both the heat and the very scarce and much-needed water,\u201d says Michael Evans, CEO of The Vines, a global network of vineyards.\u00a0\r\n\r\n\r\n\r\nIn search of water, the grapevines\u2019 roots descend into schist\u2019s rocky layers.\r\n\r\n\r\n\r\n\u201cFractured, laminated schist allows the vine roots to penetrate the cracks down as far as seven or eight meters deep, where rainwater naturally flows,\u201d says Fritsch.\r\n\r\n\r\n\r\nThis deep dive has benefits beyond hydration.\r\n\r\n\r\n\r\n\u201cOn the way, the roots absorb lots of minerals, which is known to give low yields of small grapes with thick skins but a high concentration of flavors, color, acidity and tannins,\u201d says Evans. \u201cThe result is highly intense and aromatic, often big and bold, depending on the winemaker, but always with a lot of what we call \u2018mineral\u2019 notes.\u201d\r\n\r\n\r\n\r\n\r\nOn the less advantageous side, schist lacks nitrogen and is low in organic matter like plant residues, microbial biomass and other substances that help create stable growing environments and promote biodiversity to stave off disease.\u00a0\r\n\r\n\r\n\r\nThese shortcomings don\u2019t prevent viticulturalists from growing renowned wines in schist. In addition to Priorat and Alsace, schist is associated with wine regions like the Languedoc and Loire and Rh\u00f4ne Valleys in France, as well as Portugal\u2019s Douro Valley.\u00a0\r\n\r\n\r\n\r\n\r\n\u201cGenerally speaking, it is understood that the schist reinforces the acidity in the wines,\u201d says Fritsch, who thinks this can benefit Riesling and Pinot Gris grapes in Alsace.\u00a0\r\n\r\n\r\n\r\nWinemaker R\u00e9my Gresser believes the schist soils in which he cultivates 35.5 acres of Alsatian grands crus help provide linear character and \u201ca silky touch\u201d to his finished wines.\r\n\r\n\r\n\r\nThe most common tasting note associated with schist soils is minerally characteristics. To that end, Wine Enthusiast\u2019s Anna Lee Iijima and Roger Voss cite schist soils in tandem with minerally notes in red wines from the Rh\u00f4ne and Douro Valley, respectively.