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Introduction
Howelite (Ca2B5SiO9(OH)5) and howlite (Ca2B5SiO10(OH)6) are two similar minerals that are often confused with each other. Both minerals are composed of calcium, boron, silicon, oxygen, and hydrogen, but howelite contains an additional hydroxyl group (OH-) in its chemical formula. This difference in chemical composition results in some important differences between the two minerals.
Physical Properties
Howelite is a white or colorless mineral with a vitreous to pearly luster. It is typically found in massive or nodular form, and it has a Mohs hardness of 3.5 to 4.
Howlite is a white or colorless mineral with a vitreous to pearly luster. It is typically found in massive or nodular form, and it has a Mohs hardness of 3.5 to 4.
Chemical Properties
Howelite contains an additional hydroxyl group (OH-) in its chemical formula. This difference in chemical composition results in some important differences between the two minerals.
Howlite does not contain an additional hydroxyl group (OH-) in its chemical formula. This difference in chemical composition results in some important differences between the two minerals.
Optical Properties
Howelite is transparent to translucent, and it has a refractive index of 1.55 to 1.56.
Howlite is transparent to translucent, and it has a refractive index of 1.54 to 1.55.
Crystallography
Howelite crystallizes in the monoclinic crystal system.
Howlite crystallizes in the triclinic crystal system.
Occurrence
Howelite is a relatively rare mineral that is found in only a few locations around the world. The largest deposits of howelite are found in California, Mexico, and Turkey.
Howlite is a more common mineral than howelite, and it is found in a wider variety of locations around the world. The largest deposits of howlite are found in the United States, Canada, and Mexico.
Uses
Howelite is used in a variety of applications, including:
- Jewelry making
- Decorative stone
- Pigment
- Refractory material
Howlite is used in a variety of applications, including:
- Jewelry making
- Decorative stone
- Pigment
- Refractory material
Howelite
3.5-4.0 Mohs scale of hardness
White or colorless
Vitreous to pearly luster
Monoclinic crystal system
Transparent to translucent
1.55-1.56 refractive index
Howlite
3.5-4.0 Mohs scale of hardness
White or colorless
Vitreous to pearly luster
Triclinic crystal system
Transparent to translucent
1.54-1.55 refractive index
Comparison of Properties
The following table summarizes the key differences between howelite and howlite:
| Property | Howelite | Howlite |
|---|---|---|
| Chemical formula | Ca2B5SiO9(OH)5 | Ca2B5SiO10(OH)6 |
| Crystal system | Monoclinic | Triclinic |
| Hardness | 3.5-4.0 | 3.5-4.0 |
| Luster | Vitreous to pearly | Vitreous to pearly |
| Color | White or colorless | White or colorless |
| Transparency | Transparent to translucent | Transparent to translucent |
| Refractive index | 1.55-1.56 | 1.54-1.55 |
Applications
Both howelite and howlite are used in a variety of applications, including jewelry making, decorative stone, pigment, and refractory material. However, there are some specific applications for which each mineral is better suited.
Howelite is a harder mineral than howlite, making it more suitable for use in jewelry and other applications where durability is important.
Howlite is a more common mineral than howlite, making it more readily available and less expensive.
Conclusion
Howelite and howlite are two similar minerals with some important differences. By understanding the key differences between these two minerals, you can make informed decisions about which mineral is best suited for your specific application.
