Minerality
The expression of minerality in wine is often described as earthy, flinty, stony, and “saline”. It’s a complex and sometimes elusive characteristic, but it's widely thought to be influenced by the soil in which the grapes are grown. It goes deeper (literally and figuratively), as the vines’ roots have to be deep enough to be in contact with subsoils that impart these characteristics.
SOIL COMPOSITION
The type of soil found in a vineyard plays a huge role in the flavor profile of the wine. Soil provides nutrients to the vine, and these minerals, which are absorbed by the roots, can affect the grape’s chemistry.
Clay soils can retain moisture and nutrients, often leading to wines with a rich, lush, full-bodied character. Carneros, Rioja, Tuscany, Barossa Valley, and Right bank Bordeaux are known for these soil types.
Limestone-rich soils often contribute a certain "freshness" or "brightness" to the wine, which is particularly common in regions like Burgundy and Champagne.
Gravel and sandy soils may allow for good drainage, which can stress the vines, leading to wines with more concentrated flavors. Bordeaux (gravel) and Barolo (sandy) are quite known for these soil types.
Volcanic soils are often associated with wines that have a distinct mineral character, sometimes described as iron, spice, smoke, or even a bit salty, due to the unique elements in the soil. Etna in Sicily, Moon Mountain in Sonoma, Lake County in CA, Santorini, and parts of Montalcino, Italy are known for this soil type.
MINERALS AND GRAPE EXPRESSION
While the direct impact of specific minerals like potassium, calcium, and magnesium is still debated among scientists, many believe these minerals influence the overall growth and stress levels of the grapevine. When vines are stressed, particularly by poor soil conditions, they often produce fewer but more concentrated grapes, which can lead to more complex flavors in the wine.
Additionally, certain minerals may interact with the vine’s ability to absorb water or other nutrients, affecting the acidity or sugar levels in the grapes, which are key components of flavor.
SOIL AND TERROIR
The concept of terroir is central to the idea of minerality in wine. Terroir refers to the entire environmental context of a vineyard, including soil, climate, topography, and local ecosystem. The soil acts as a crucial part of the terroir, shaping how the vine interacts with the environment. The interaction between the soil and the vine affects grape ripening, stress, and the resulting flavor profile, which in turn can translate into a wine that showcases distinct "mineral" notes.
It is the widely held belief that encouraging deeper vine root growth through certain viticultural techniques, such as dry farming, will take minerality from the soil to what you are tasting in the glass more clearly. Dry farming is one of the best and direct ways to gain true minerality in wine. If the roots do not go deeper than the topsoil (which is typically 6 inches - 3 feet), there is little to no chance to extract minerality from the soil, which offers greater complexity in a wine. By utilizing this practice, you can extract the attributes of the soil that you have. For example, volcanic basalt expresses an iron and savory expression with great tension and liveliness to the wine.
SOIL AND AROMATIC QUALITIES
The mineral qualities often described in wine — such as flint, wet stone, or gunflint — can stem from the soil types and the way they influence the aromatic precursors in the grapes. These aromatic compounds can then be released during fermentation and maturation, contributing to the overall minerality. This is particularly noticeable in whites like Chablis or Riesling, where the terroir and mineral-rich soils often bring out a crisp, stony finish.
TERROIR VS. WINEMAKING
It’s important to note that while soil plays an important role, winemaking techniques can also amplify or mask the minerality of a wine. For instance, fermentation in oak barrels might overshadow subtle mineral notes, while stainless steel fermentation often allows for more purity and expression of the grape’s terroir.
Essentially, the soil in vineyards helps shape the minerality of wine by providing the minerals that the vines absorb, influencing the composition of the grape and how it ripens. Great wines that have minerality possess a tension in them or “lift” which gives wine a vibrancy and liveliness. Understanding how soil and other aspects of terroir affect wine can provide deeper insight into a wine's character, adding another layer of appreciation for the complexity of viticulture.