Howlite is scientifically defined as a calcium borosilicate hydroxide, a distinct borate mineral that forms naturally in evaporite deposits. Whether Howlite qualifies as a true gemstone depends on the criteria used for classification. Its acceptance as a “gemstone” differs between the strict standards of mineralogy and the broader definitions used in the commercial jewelry market. This distinction is based on the stone’s physical properties and its use as an ornamental material.
Defining Howlite’s Mineralogical Identity
Howlite forms primarily as irregular, opaque nodules, rather than distinct crystals. It is a borate mineral typically found in evaporite deposits, which are remnants of ancient saline water bodies. Most commercial material originates from sites in California and Canada.
The natural color of Howlite is soft white or gray, characterized by fine gray, black, or dark brown veining that creates a distinctive web-like pattern. A defining physical characteristic is its relative softness, registering only a 3.5 on the Mohs scale of hardness. This low durability is a significant factor in its scientific classification, making the stone vulnerable to scratches and impacts.
The Commercial vs. Scientific Classification of Gemstones
Scientifically, a mineral must possess a high degree of beauty, durability, and rarity to be considered a traditional gemstone. Howlite meets the beauty and natural origin criteria, but its low Mohs hardness of 3.5 means it lacks the necessary durability for a classic gem like a diamond (10) or quartz (7). Therefore, under a strict gemological definition, Howlite is classified as an ornamental mineral, not a precious gemstone.
However, the jewelry industry uses a much wider, more inclusive definition for a gemstone. Commercially, a “gemstone” is any mineral or rock material that is cut, polished, or otherwise prepared for use in jewelry or decorative objects. This commercial classification includes a vast range of materials, such as pearls, amber, and softer minerals like Howlite, that do not meet the stringent scientific durability standard. Because Howlite is attractive when polished and is widely used for beads and cabochons, it is accepted as a commercial gemstone.
Primary Uses in Jewelry and Imitation
Howlite is valued for its versatility. Its most common role in the market, however, is as a substitute for more expensive stones. The porous nature of the material makes it exceptionally absorbent, allowing it to be easily dyed a variety of colors.
It is most famously dyed blue to mimic turquoise. The natural gray-black web-like veining in Howlite closely resembles the matrix found in genuine turquoise, which contributes to its effectiveness as an imitation. Howlite is also dyed deep blue to simulate lapis lazuli or red to imitate coral, serving as an affordable alternative for jewelry designs.