Howlite, a mineral frequently used in jewelry and decorative objects, is valued for its white, marble-like appearance. This borate mineral is commonly dyed to mimic more expensive stones, such as turquoise or lapis lazuli. Understanding the material’s unique chemical and physical properties is important for preserving its structural integrity and aesthetic quality. Improper exposure to moisture presents specific risks that can permanently alter this relatively soft stone.
Understanding Howlite’s Mineral Makeup
Howlite is classified as a borate mineral with a specific chemical formula of \(\text{Ca}_2\text{B}_5\text{SiO}_9(\text{OH})_5\). This composition places it among minerals formed in evaporite deposits, which are created by the evaporation of mineral-rich water. Its geological origin in arid environments suggests a natural sensitivity to prolonged moisture exposure.
The stone’s structure is relatively soft, registering approximately 3.5 on the Mohs scale of mineral hardness. This low hardness means the material is easily scratched and structurally vulnerable compared to harder gemstones.
A defining characteristic of howlite is its naturally porous structure. The stone contains microscopic spaces that allow liquids to penetrate the surface. This porosity is precisely why howlite is so easily and effectively dyed for use as a simulant, as the colorant is readily soaked up by the stone.
The presence of borate and calcium within its chemical structure makes the material susceptible to chemical alteration when exposed to water, especially if the water is acidic or contains dissolved impurities. While howlite is not immediately soluble, long-term or repeated saturation can compromise the bonds within the crystal lattice. This structural weakness is the underlying scientific reason for caution regarding howlite and water.
The Effects of Water on Howlite
Submerging howlite in water, particularly for extended periods, can lead to structural degradation and aesthetic ruin. The porous nature of the stone acts like a sponge, drawing water deep into the matrix. This prolonged saturation softens the mineral, making it more prone to physical damage.
The absorption of moisture can lead to a phenomenon known as micro-fissuring, where tiny cracks develop within the stone. Over time, this weakening can cause the polished surface to dull, or in severe cases, result in chipping or splintering along the stone’s edges. Borate minerals can also react slowly with water, leading to a subtle dissolution of the surface material and a loss of the original luster.
A significant aesthetic concern, especially for the commonly available blue or green versions, is dye leakage. Since howlite is almost always dyed to imitate turquoise or other stones, submerging it in water causes the artificial colorant to bleed out of the pores. This leaves the howlite piece with faded, patchy, or permanently stained areas.
If the water used for cleaning is “hard,” containing high concentrations of minerals like calcium and magnesium, it can leave behind residue inside the pores. As the water evaporates, these mineral deposits remain, leading to a cloudy appearance or a white film that is difficult to remove.
Exposure to chlorinated tap water or salt water is particularly damaging. The chemical agents or abrasive salts accelerate both the structural and aesthetic deterioration of the soft, porous material.
Safe Alternatives for Cleaning and Care
To maintain howlite’s appearance and integrity, dry cleaning methods are recommended. Gentle, routine maintenance can be performed using a soft, dry cloth to wipe away surface dust and oils. This simple action prevents the buildup of grime that could otherwise necessitate deeper cleaning.
If a more thorough cleanse is required, the contact time with moisture must be minimal. Use a cloth that is only slightly dampened, not soaking wet, with a small amount of mild, pH-neutral soap. The stone should be quickly and gently wiped, focusing only on the soiled areas.
Immediately following any contact with moisture, the howlite must be dried thoroughly with a clean, soft towel. This prevents water from lingering in the pores. The goal is to lift the grime without allowing the moisture to penetrate beyond the surface.
Proper storage is also a simple, effective form of care. Howlite should be kept away from high-humidity areas, such as bathrooms, which can introduce moisture. It is important to store it separately from harder stones, like quartz or amethyst, to prevent scratching its softer surface.