What is the Difference Between Howlite and Magnesite

The key difference between howlite and magnesite is that howlite is comparatively less strong, whereas magnesite is stronger.

Both howlite and magnesite are not known for their durability because of their hardness values. However, we can compare their strength as metals with respect to the Mohs scale hardness.

1. Overview and Key Difference
2. What is Howlite
3. What is Magnesite
4. Howlite vs Magnesite in Tabular Form
5. Summary – Howlite vs Magnesite

What is Howlite?

Howlite is a calcium borosilicate material that occurs as a hydroxide. The chemical formula can be given as Ca₂B₅SiO₉(OH)₅. It is a borate mineral that can be found in evaporite deposits. The hardness of this substance can be given as 3.5 on the Mohs scale of hardness. It has a monoclinic crystal structure, and the crystal class is prismatic (2/m). It has a white to colorless appearance. Its crystal habit can be described as massive to nodular, which occurs as tabular prisms that are flattened to [100].

The fracture of howlite can be given as conchoidal and uneven. Its luster is subvitreous and glimmering. The streak of this mineral is white, and the optical properties can be given as translucent. The specific gravity ranges between 2.53 and 2.59.

Howlite is commonly important in the jewelry industry in making decorative objects such as small carvings and jewelry components. It has a porous texture that can be easily dyed, imitating other materials. E.g. turquoise. This is because of the superficial similarity of the veining patterns.

What is Magnesite?

Magnesite is a mineral substance having the chemical formula MgCO₃. However, there can be some amounts of iron, manganese, cobalt, and nickel that can occur as admixtures. We can categorize magnesite as a carbonate mineral, and its crystal system is trigonal. It appears in colorless, white, pale yellow, pale brown, faintly pink, lilac rose, etc., according to the composition. The crystal habit is usually massive, but rarely it can be hexagonal prisms or rhombohedrons.

The fracture of magnesite is conchoidal, and the nature is brittle. It has a vitreous luster and white streak color. It can be transparent to translucent. The specific gravity can be given in the range of 3.0 – 3.2. The hardness ranges between 3.5 – 4.5. This material is infusible, and it can undergo effervescence in hot HCl. Besides, it can show pale green or pale blue fluorescence as well as phosphorescence under UV light.

Magnesite can be found as veins in ultramafic rocks, serpentinite, magnesium-rich rocks, etc. Often, magnesite is cryptocrystalline, and it contains silica as opal or chert. Magnesite is present within the regolith above ultramafic rocks in the form of secondary carbonates (in soil and subsoil). It occurs as deposits that form from the dissolution of magnesium-bearing minerals through carbon dioxide in groundwaters.

The most common form of magnesite is the isotopic structure. It is controlled by several factors, such as the conversion from hydrous Mg-carbonates to magnesite, disequilibrium, mineral structure, and later thermal effects, etc.

When considering the formation of magnesite, it forms from talc carbonate metasomatism of peridotite and other types of ultramafic rocks. Moreover, magnesite forms from the carbonation of olivine when there is sufficient water and carbon dioxide amounts present at elevated temperatures and high pressure.

What is the Difference Between Howlite and Magnesite?

Howlite and magnesite are two types of minerals with different hardness and strengths. The key difference between howlite and magnesite is their strength. Howlite is less strong than magnesite. Howlite has a hardness value of less than 3.5 on the Mohs hardness scale, while magnesite has a value of 4 – 4.5 on the Mohs hardness scale.

Below is a summary of the difference between howlite and magnesite in tabular form for side-by-side comparison.

Summary – Howlite vs Magnesite

Howlite is a calcium borosilicate material that occurs as a hydroxide, while magnesite is a mineral having the chemical formula MgCO₃. The key difference between howlite and magnesite is that magnesite is comparatively stronger than howlite.

Reference:

1. “Magnesite.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.

Image Courtesy:

1. “Howlite” By Ronnie Van Dommelen – self-made (CC BY-SA 3.0) via Commons Wikimedia
2. “Magnesite-121892” By Rob Lavinsky, iRocks.com – (CC-BY-SA-3.0) via Commons Wikimedia