Barite

Barite is a barium sulfate mineral (BaSO₄), notable for its high density, which earned it the old name heavy spar. Barite precipitates from barium-rich fluids, typically in hydrothermal veins, sedimentary deposits, and as a gangue mineral alongside metallic ores. It can also form at the interface of barium-bearing groundwater and sulfate-rich water.

The variety of crystal forms is remarkable. In Morocco, thin tabular crystals grow in spectacular clusters on lead mineral substrates. In South Dakota, barite forms rosette-shaped concretions within clay deposits as barium-rich groundwater meets sulfate in the soil. In England's Lake District, honey-yellow and blue crystals formed in lead-zinc veins alongside fluorite and galena.

Barite is the primary ore of barium and has a major industrial use: its extreme density (4.48 g/cm³, making it noticeably heavy) makes it the preferred weighting agent for drilling mud in oil and gas exploration. Over 80% of barite produced globally goes to the petroleum industry.

Barite's most distinctive feature is its surprisingly high density for a non-metallic mineral. Pick up a barite specimen and it feels much heavier than expected. This, combined with relatively low hardness (3.5) and tabular or prismatic crystal habit, makes identification straightforward.

Distinguish from celestite (very similar but lighter SG of 3.95, often blue), calcite (lower SG, effervesces in acid), and feldspar (harder, different cleavage). Barite has perfect cleavage in two directions at nearly 90 degrees.