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Geologic Occurrence
The formation of rhodochrosite usually occurs in fractures and cavities of metamorphic and sedimentary rocks. It is often associated with silver deposits, and a few silver mines produce rhodochrosite as a byproduct. Some of the common modes of occurrence and their lapidary uses are described below. In metamorphic rocks, rhodochrosite is found as a vein and fracture-filling mineral where it precipitates from…
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Physical and Chemical Properties
Rhodochrosite has a variable chemical composition. It is a manganese carbonate, but the manganese is frequently replaced by iron, magnesium and/or calcium as shown in this formula: (Mn,Fe,Mg,Ca)CO3. These substitutions of other elements for manganese change the composition and alter the specific gravity, hardness, and color of the mineral. The bright pink color can become grayish,…
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What is Rhodochrosite?
Rhodochrosite is a manganese carbonate mineral that ranges in color from light pink to bright red. It is found in a small number of locations worldwide where other manganese minerals are usually present. Rhodochrosite is sometimes used as an ore of manganese but is rarely found in economic quantities. Specimens with a wonderful pink color are used to produce highly…
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Grape, Yes. Agate, Maybe Not.
The name “grape agate” has stuck as a marketing term. However, the name is a misnomer. Misnomers are names that are scientifically incorrect. There are no arguments with “grape” because of its purple color. But, the use of “agate” as a species/variety name draws objections. Here is an analysis… Grape Agate: This name is inappropriate because agate should…
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What Is Grape Agate?
Grape agate is a marketing name for purple aggregates of tiny quartz crystals with a spherical (botryoidal) habit. The name reflects their purple color and how they occur in clusters that resemble bunches of grapes. This material is found in the Mamuju area, near the western coast of Sulawesi, an island of Indonesia. Grape agate entered the mineral market…
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Consumers and Synthetic Diamonds
Synthetic diamonds have been the dominant type of diamond in industrial applications since the end of the 20th century. Most of the diamonds used to make abrasives and cutting tools are now synthetic. Virtually all diamonds used to make windows, speaker domes, heat sinks, low-friction microbearings, wear-resistant parts, and other technology products are now synthetic.…
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Synthetic Diamonds
Diamond is a very valuable material, and people have been working for centuries to create them in laboratories and factories. Synthetic diamonds are man-made materials that have the same chemical composition, crystal structure, optical properties and physical behavior as natural diamonds. Other names used for synthetic diamonds include: “lab-grown,” “lab-created,” and “man-made”. These names properly indicate that…
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Diamond Simulants
Diamond simulants are materials that look like diamond, but they have different chemical compositions. Diamond simulants can be natural materials such as colorless zircon or sapphire. More often they are man-made materials such as cubic zirconia (ZrO2), moissanite (SiC), YAG (yttrium aluminum garnet Y3Al5O12), or strontium titanate (SrTiO3).
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How Hard Is Diamond?
Although diamond is known as the world’s hardest natural material and has been assigned a hardness of 10 on the Mohs hardness scale, that information is an oversimplification. Diamond crystals vary in hardness by direction. Mineral Hardness Scales Mineral Mohs Vickers(kg/mm2) Talc 1 27 Gypsum 2 61 Calcite 3 157 Fluorite 4 315 Apatite 5 535…
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Other Uses of Diamonds
Most industrial diamonds are used as abrasives. However, diamonds are used in many other applications. Diamond windows are made from thin diamond membranes. They are used to cover openings in lasers, x-ray machines, and vacuum chambers. They are transparent, very durable, and resistant to heat and abrasion. Diamond speaker domes enhance the performance…