Minerals in Food: Essential Dietary Minerals

## From Rocks to Nutrition

The "minerals" in your food are the same elements found in geological minerals. Weathering breaks down rocks, releasing elements into soil, where plants absorb them and introduce them into the food chain. Understanding this geological cycle reveals why certain soils produce nutrient-rich crops.

## Major Dietary Minerals

| Nutrient | Daily Need | Geological Source | Source Mineral | Function |
|----------|-----------|-------------------|----------------|----------|
| Calcium | 1,000 mg | Limestone soils | Calcite (CaCO₃), apatite | Bones, nerve signaling |
| Phosphorus | 700 mg | Phosphatic rock | Apatite (Ca₅(PO₄)₃(F,OH)) | DNA, ATP, bones |
| Potassium | 2,600 mg | Feldspar weathering | Orthoclase (KAlSi₃O₈) | Nerve function, fluid balance |
| Sodium | 500 mg | Evaporite deposits | Halite (NaCl) | Fluid balance, nerves |
| Magnesium | 400 mg | Dolomite, olivine soils | Dolomite (CaMg(CO₃)₂) | 300+ enzymatic reactions |
| Sulfur | ~900 mg | Volcanic soils | Native sulfur (S), pyrite | Amino acids (cysteine, methionine) |

## Trace Elements

| Nutrient | Daily Need | Geological Source | Crystal System |
|----------|-----------|-------------------|----------------|
| Iron | 8–18 mg | Hematite (Fe₂O₃), magnetite | Trigonal, Cubic |
| Zinc | 8–11 mg | Sphalerite (ZnS) | Cubic |
| Copper | 0.9 mg | Chalcopyrite (CuFeS₂) | Tetragonal |
| Manganese | 2.3 mg | Pyrolusite (MnO₂) | Tetragonal |
| Selenium | 55 µg | Selenide minerals | Various |
| Iodine | 150 µg | Iodine-bearing brines | — |
| Chromium | 35 µg | Chromite (FeCr₂O₄) | Cubic |
| Molybdenum | 45 µg | Molybdenite (MoS₂) | Hexagonal |

## Soil Mineralogy and Crop Nutrition

### Why Location Matters

Soil mineral content determines crop nutrition:

- **Basalt-derived soils** (Hawaii, Iceland): Rich in iron, magnesium, calcium from olivine and pyroxene weathering
- **Granite-derived soils** (New England, Scandinavia): Rich in potassium from feldspar, but often acidic
- **Limestone soils** (Champagne, Kentucky): High calcium, high pH, excellent for grapes and grasses
- **Volcanic soils** (Campania, Java): Extremely fertile, rich in trace elements

### Mineral Deficiency in Soils

| Deficient Element | Geological Cause | Health Impact |
|-------------------|-----------------|---------------|
| Iodine | Distance from ocean, leached soils | Goiter (hypothyroidism) |
| Selenium | Low-selenium parent rock | Keshan disease |
| Zinc | Alkaline, calcareous soils | Growth retardation |
| Iron | Waterlogged/alkaline soils | Anemia |

## Table Salt: The Most Direct Mineral-Food Connection

Table salt (NaCl) is the mineral halite, directly mined or evaporated from seawater. It crystallizes in the cubic system with perfect cubic cleavage, Mohs 2.5, and a specific gravity of 2.17. Global production exceeds 300 million tonnes annually.