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Luster Is Not Diagnostic
Luster is not a diagnostic property. This means that, for most mineral species, luster can vary from one specimen to another. For example: hematite can exhibit a metallic luster, a submetallic luster, or a dull luster. A single specimen can exhibit one or more of these lusters. Because of that, luster cannot be heavily relied…
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Commercial Use of Luster
Many minerals used in commercial products owe their value and popularity at least in part to their luster. The best example is gold. It has a highly reflective metallic luster that resists tarnish. That beautiful luster makes gold the perfect metal for jewelry manufacturing. Today, most of the world’s gold is made into jewelry. Muscovite…
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Types of Luster
The photographs and descriptions on this page illustrate some of the most common lusters observed in minerals. Metallic Luster Specimens with a metallic luster exhibit the reflectivity and brightness of a metal and are always opaque. The smoother the surface, the brighter their luster, and the higher their reflectivity. When a beam of incident light is reflected…
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How to Observe Luster
The luster of a mineral is best observed on a surface that is free of moisture, dirt, tarnish, and abrasion. Geologists in the field usually carry a rock hammer to break rocks so that their true luster and color can be observed. Breakage is usually not necessary when observing the luster of cleaned and cared-for specimens in a laboratory or classroom.…
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What Is Luster?
Luster is a word used to describe the light-reflecting characteristics of a mineral specimen. The luster of a specimen is usually communicated in a single word. This word describes the general appearance of the specimen’s surface in reflected light. Eleven adjectives are commonly used to describe mineral luster. They are: metallic, submetallic, nonmetallic, vitreous, dull, greasy, pearly, resinous,…
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The Value of Infrared Telescopes
“Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together,” said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. The Spitzer observations were made before it used up its liquid coolant in…
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Jets Transport Crystals Through Solar Systems
Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European…
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Forsterite Crystals
The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a peridot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA’s Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets. “If you could somehow transport yourself inside…
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Temperatures as Hot as Lava
“You need temperatures as hot as lava to make these crystals,” said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. “We propose that the crystals were cooked up near the surface of the…
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Descending Olivine Crystals
Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA’s Spitzer Space Telescope. This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely…