What do rough gemstones look like

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Download Article Explore this Article methods. Related Articles. Method 1. All rights reserved. This image may not be used by other entities without the express written consent of wikiHow, Inc. Set a streak plate flat on a table to perform a streak test. A streak test is a method used to find the color of a stone or mineral in powdered form. A streak plate is a square of unglazed porcelain that has a rough surface you can use to help identify the gemstone. Wash and dry the stone to remove dirt and dust.

Rinse it well under clean water and use your fingers to rub the surface clean. Then, dry it well with a clean towel. Place a point of the gemstone against the streak plate. Hold the gemstone in your dominant hand and use your other hand to stabilize the streak plate. Choose a point or protrusion on the stone that you can use to make a thin line across the plate.

Hold the point against the plate. Drag the gemstone across the plate in 1 motion. Apply pressure with your dominant hand and pull the stone over the surface of the streak plate.

Use 1 motion to grind the stone over the surface and leave behind a thin line of powder from the stone. Amethyst, Calcite etc. Etching and Dissolution : In general, a great many crystals show light to moderate local dissolution, commonly called etching, usually seen as numerous pits, imparting a frostiness to the faces, or as distinct pits scattered on the otherwise smooth face.

Close inspection reveals relationships to the underlying atomic structure. Thus, the hexagonal pits on beryl itself and their shape are regulated by the beryl structure. On the other hand, the boat shaped indentations on the prism faces are not nearly so diagnostic.

Since every crystal is a neatly balanced structure of like atoms in like positions, it follows that such pits must look the same when present on identical crystal faces. For example, in a cubic mineral the same atomic pattern lies beneath all cube faces. If one face is partly dissolved and covered with small square pits, all other faces will develop exactly the same kind of pits if attacked by the same solution.

This is of great importance in identifying like faces when examining etched crystals. By turning over a severely corroded specimen, it is sometimes possible to orient the crystals correctly from noting that pits of similar shape appear only in certain directions. Oscillatory Striations : Crystals of pyrite, quartz and tourmaline are commonly covered by numerous grooves and striations. Because several faces are trying to develop simultaneously upon the same crystal area, it is called oscillatory growth.

All three species, quartz, pyrite and tourmaline can be identified with a high degree of confidence when these characteristic markings are present on the crystals.

Quartz exhibits lateral striations on the prism faces, Tourmaline exhibits deep vertical grooves or striations on the prism faces while pyrite exhibits three sets of parallel striations on adjacent faces. Aggregates : Growth of crystals in a confined space results in a crystalline aggregate of interlocked grains without crystal forms.

Brenner is also a published sci-fi author. She graduated from San Diego's Coleman College in Massive minerals without a definite shape Botryoidal minerals that look like a grape bunch Reniform-shaped minerals that resemble the shape of kidneys, like the hematite stone Tabular minerals that have a flat crystal shape Acicular minerals that appear as thin, needlelike crystals.

Flat flakes break in one piece Rhombic breakage occurs on several planes at diagonal angles Cubic chips refer to stones that break across three planes at right angles Long blocks result in breakage in two planes.

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