1.22 ct PARGASITE - TANZANIA

Pargasite

Pargasite is a gemstone that captures the lush, vibrant essence of the metamorphic world. A complex member of the Amphibole supergroup, it is often found as stout, prismatic crystals in marble or skarn deposits. I have always been particularly taken by the "Chrome Pargasite" variety; its intense, emerald-green hue is so vivid it can easily be mistaken for fine Tsavorite Garnet or Chrome Diopside. Faceting Pargasite is a sophisticated task for any lapidary, as its distinct amphibole cleavage requires careful orientation to prevent the stone from splitting. When cut correctly, however, it offers a rich, vitreous luster and a depth of color that makes it a "secret" favorite among those who look beyond the traditional precious stones. It is a mineral of high-temperature origins that brings a refreshing, electric energy to any specialized collection.

The Heritage & Discovery

Historical Significance: Pargasite is a key mineral for understanding the conditions of the Earth's upper mantle and lower crust. Historically, it has been used by geologists to track the presence of water and fluorine in high-pressure metamorphic environments. It represents a specific "geothermometer," helping us unlock the temperature history of the mountains in which it formed. In the world of rare gems, it is prized as one of the most colorful and "clean" members of the often dark and opaque amphibole family, standing as a testament to the chemical diversity possible within a single mineral group.

Discovery: The mineral was first identified in 1814 and was named after its type locality in Pargas (Parainen), Finland. Its discovery allowed mineralogists to begin categorizing the incredibly complex "hornblende" series into more specific species based on their sodium and aluminum content. Since its identification in the Finnish marbles, it has remained a hallmark of classic European mineralogy.

Important Mines: While the original Finnish locality is historic, the most spectacular gem-quality material today comes from the Mogok Stone Tract in Myanmar and the Hunza Valley in Pakistan. These regions produce the rare, transparent Chrome Pargasite that I find so captivating. I also keep an eye on specimens from the Luc Yen district in Vietnam. I prioritize the Burmese and Pakistani material for our documentation, as the combination of intense chromium-driven color and high transparency is simply unmatched anywhere else in the world.

Mineralogical Profile

Description: Pargasite is a complex sodium calcium magnesium aluminum silicate hydroxide that crystallizes in the monoclinic system. It sits at a 5 to 6 on the Mohs scale , making it suitable for protected jewelry or high-end display. It is characterized by its vitreous luster and its range of colors, from dark forest green and brown to the highly sought-after vibrant "neon" green.

One of its most identifying traits is its typical amphibole cleavage, with planes meeting at approximately 56° and 124°. This geometric signature is a key way to distinguish it from the pyroxene group (like Diopside). Because it is often rich in fluorine, it is remarkably stable at high temperatures. When faceted, it exhibits a pleochroism that can shift from light yellow-green to deep emerald, giving the stone a "living" quality as it moves in the light. It is a dense, chemically complex mineral that offers a sophisticated alternative to more common green gemstones.

Chemical Formula: NaCa ₂ (Mg ₄ Al)(Si ₆ Al ₂ )O ₂₂ (OH) ₂