Howlite is a soft, porous mineral composed of calcium borosilicate hydroxide, typically found in irregular nodules that can resemble a head of cauliflower. Discovered in Nova Scotia in 1868, this mineral has gained popularity in jewelry and decorative objects due to its ability to take a smooth polish. Its porous nature leads to a dramatic difference between its natural coloration and the vibrant states commonly seen in the market.
Howlite’s Natural Appearance
The natural, undyed color of howlite is an opaque, chalky white or a milky, pale gray. This coloration stems from its chemical composition as a borate mineral. Its luster is sub-vitreous, meaning it has a slight glassiness, or earthy, giving it a porcelain-like texture.
Natural howlite is characterized by an intricate network of matrix veining that runs throughout the stone. These veins are typically dark gray, black, or deep brown, creating an erratic, web-like pattern across the white base.
The mineral is quite soft, measuring only 3 to 3.5 on the Mohs scale of hardness, making it susceptible to scratches. This softness and inherent porosity—the presence of minute, interconnected holes—make it ideal for color treatments.
The Purpose and Process of Dyeing Howlite
Howlite is dyed primarily to serve as an inexpensive imitation for more valuable materials. The most common transformation involves dyeing the stone a robin’s egg or sky-blue color to mimic turquoise, often sold as “turquenite.” It is also frequently dyed a deep blue to simulate lapis lazuli or a vivid red to substitute for coral.
The dyeing process involves soaking the prepared howlite material in a solution of specialized colorants. Some methods suggest gently heating the stone first to remove internal moisture, maximizing absorption. As the dye penetrates, the natural dark matrix veining absorbs the color differently, often remaining darker than the surrounding body. This helps maintain the appearance of natural veining found in stones like genuine turquoise.
Beyond blue and red, howlite is also dyed in a wide spectrum of colors, including purple, yellow, and green, to create brightly colored jewelry. While the dye penetrates the surface layer effectively, it often does not reach the core, meaning the interior of the stone typically remains the original white color.
Distinguishing Natural from Dyed Stones
A primary method for distinguishing between a dyed howlite and the natural stone it imitates is the “rub test” using a solvent. Applying acetone, such as nail polish remover, to an inconspicuous area will cause the dye to transfer onto the cotton swab.
Examining the color consistency can also provide strong clues, as dyed howlite often displays an overly uniform or “too perfect” coloration. Genuine turquoise, for example, typically exhibits natural variations and slight inconsistencies in its hue. In contrast, the dye can sometimes pool in fissures or cracks, creating unnaturally dark spots where the color is most concentrated.
A significant physical difference is the hardness of the materials. Since howlite is only 3.5 on the Mohs scale, it is much softer than genuine turquoise, which rates between 5 and 6. If the piece is ever cut or broken, the original white interior of the howlite will be exposed, confirming it is a dyed material.