How to Identify Metallic Crystals

The metallic crystal pyrite has been nicknamed "fool's gold" for its resemblance to the precious mineral.

Copper, gold, iron, silver and mercury are some common metallic crystals. With more than 3,000 basic minerals that can combine to create countless variations, identifying minerals is no easy task. Recognizing metallic crystals involves more than simply looking for shiny rocks. But a reflective surface --- or luster --- is one of the properties to look for when identifying metallic crystals.

Instructions

1. 

   Metallic crystals, such as gold, are shiny and reflect light.

   Look for rocks and minerals with shiny surfaces. Metallic crystals are highly reflective and opaque. Examples of minerals with this metallic luster are gold, pyrite and silver.

2. 

   Silver is relatively soft compared to other metallic crystals.

   Test the hardness of the rock or mineral. Most metallic crystals are very hard. However, some minerals, such as gold and silver, are relatively soft.

3. 

   Mercury has a lower boiling point than most metallic crystals.

   Test the response of the rock or mineral to high heat. Most metallic crystals have very high melting and boiling points. There are exceptions, such as mercury, that have lower boiling points.

4. 

   Metallic crystals, such as copper, are good heat conductors.

   Evaluate the specimen's conductivity. Metallic crystals conduct heat and electricity.

5. 

   The malleability of gold enables it to be pounded into extremely thin sheets of gold leaf.

   Investigate the ability of the mineral to be shaped and stretched thin. Metallic crystals are malleable, meaning they can be pounded into thin sheets. They are also ductile. Ductility refers to a metal's ability to be stretched thin into a wire. Gold is the most malleable and ductile of all metals. A single gram of gold can be stretched into a wire 3.2 kilometers long. Gold can be hammered out into a flat sheet only four-millionths of an inch (100 nanometers) thick.

6. 

   The distinctive copper-red color of copper makes it easy to identify.

   Note the color of the specimen. Different minerals create different colors. Common metallic colors are gold and yellow (gold, pyrite); copper or copper red (copper); bronze (nickel ore); silver, silvery yellow, silvery gray, bright silver, dark silver and black (galena or silver); and peacock feathers and rainbow (bornite and peacock ore).

References

• Gems4Friends: Identifying Crystals and Minerals
• RocksForKids: Identifying Minerals
• mindat: Pyrite
• BBC: The Guide to Life, The Universe and Everything: Gold