The kaolin group consists of several minerals that share somewhat similar characteristics. Dickite mineral is one of the minerals in the groups. It has a similar composition to kaolinite but the crystal structure is different. Although this mineral is considered among the most common in its group, there are many interesting things to know.
Properties of the Dickite Mineral
The mineral’s chemical formula is Al2(Si2O5)(OH)4. It comprises 46.54% silicon dioxide, 39.50% aluminum oxide, and 13.96% water. Dickite is the polymorph of kaolinite and was reportedly formed in temperatures ranging from 86–96°C. Commonly, the mineral develops from weathering muscovite and feldspars.
People describe it as a phyllosilicate clay mineral with a monoclinic crystal structure. The crystal structure consists of three axes with varying lengths. One of those angles is perpendicular to the other two. Dickite’s crystal structure is not unlike gypsum and azurite.
The original color of dickite mineral is white or pearly, but impurities often mar it so you will see variations of colors in nature. The most common tints seen on the mineral are blue, gray, or yellowish brown. Impurities in the mineral are commonly caused by the presence of titanium, magnesium, iron, calcium, and potassium.
According to the Mohs hardness scale, the mineral is at 1.5-2. It is less hard than human fingernails and also quite vulnerable to scratches. This mineral has a recorded specific gravity of 2.60, meaning it will sink when placed in water.
What are the Uses of Dickite Mineral?
To some people, dickite has various benefits. Here are some of the most common uses of the mineral in our lives:
1. Filler Material
In the manufacturing industry, it is common to use filler material to cut costs. Filler material enables companies to reduce the use of expensive main ingredients while not compromising the quality of the production. Manufacturers that may require this filler are paint, rubber, and paper companies.
Dickite is also a popular carving medium for certain artists. These artists prefer this mineral because they do not have to exert too much effort to carve on it. This mineral is also relatively cheap compared to other carving gems. Several temples in Thailand, for example, display carving art made of dickite.
3. Potential as Pozzolan
It was found that dickite also has the potential as a pozzolan, which is a sort of adhesive material in construction. To be a pozzolan, dickite mineral must be grounded into a fine powder and processed. Past research showed that the mineral must be calcined at a higher temperature (up to 650°C). This particular issue requires further studies.
4. Indicator of Gold in Mining
The mineral is also very useful in the mining industry because its presence may provide a signal for gold in the area. Expert miners often utilize dickite to do an alteration mapping to determine the location of ore deposits. This method can save the mining company money before they pour investment into recovering the gold.
The Dickite Mineral’s Origin and Grading Examples
The name “dickite” came from the first metallurgy expert describing the mineral, Allan Brugh Dick. Dick studied kaolin on the Isle of Anglesey in Wales when he encountered this mineral in 1888. Two other experts, Clarence S. Ross, and Paul F. Kerr realized that the mineral was different from kaolinite and nacrite in 1931.
In addition to being found in Wales, there are sightings of dickite in other countries— China, Jamaica, Italy, Germany, Belgium, Thailand, the United States, and Canada. These countries have different ways of treating dickite, especially when it comes to grading.
Thailand, for example, recognizes three grades of dickite in its market. The three grades of the mineral are:
- Grade A: has a beautiful cream or cream-red color, waxy appearance, and translucency; suitable for carving.
- Grade B: has a breccia-like appearance and shows a significant amount of impurities; the most common material for carving due to affordability.
- Grade C: has a dull color and is very brittle in texture; not used for carving.
When encountering dickite in nature, experts need to test it due to its similarities with other minerals. The common modern tests that they have often done are Raman spectroscopy, XRD, and FTIR.
Despite being highly available in several parts of the world, the use of dickite mineral is still relatively scarce compared to others within the group. It is very likely that as time goes by, there will be more useful discoveries made about the phyllosilicate mineral.