Shop Windows to the Universe

We now offer the Cool It! card game in our Science Store. Cool It! is the new card game from UCS that teaches kids about the choices we have when it comes to climate change.
Hornblende, a type of amphibole
Click on image for full size
Windows to the Universe

Amphibole

There are several different minerals within the amphibole group, but the most common type is hornblende. You can find small crystals of hornblende in many types of igneous rocks. They often look like little dark specks. Use your hand lens or magnifying glass to see the crystal shapes.

Hornblende

  • Shape: Monoclinic (crystals look like short, six-sided columns)
  • Luster: Glassy or milky
  • Color: Black or dark green, translucent to opaque
  • Streak: Grey-green or grey-brown
  • Hardness: 5-6 on Mohs Hardness Scale
  • Cleavage: Two planes that meet at a 124-degree angle
  • Fracture: Uneven brittle fracture


Last modified April 16, 2003 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

TES XXVI, 3 fall 2010 The Fall 2010 issue of The Earth Scientist, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Bowen's Reaction Series

As magma cools, elements within it bond together to form crystals of minerals. However, not all minerals can form at the same time during cooling. Some minerals grow when magma is still pretty hot, while...more

What’s That Mineral?

Spotting minerals is fun! There are many different types of minerals, each with a different name and a special set of characteristics. So, if you find a mineral that you do not recognize, you can use...more

Quartz

Quartz is one of the most common mineral in Earth’s crust! Silica (Si) and Oxygen (O) are the only elements within pure quartz. If a cooling magma has silica leftover after feldspars form, quartz is likely...more

Mica Minerals

Mica minerals make some rocks sparkle! They are often found in igneous rocks such as granite and metamorphic rocks such as schist. They sparkle because light is reflected on their flat surfaces, which...more

Feldspar

Feldspar is the most common mineral in the Earth’s crust, so you are very likely to find it in the rocks you collect! It is found it all of the three rock types, but is most common in intrusive igneous...more

Olivine

Olivine looks like little green crystals. It is typically found in some igneous and metamorphic rocks. Often the crystals are so small that you need to use your hand lens or magnifying glass to see them...more

Type of Minerals

So far, over 2000 minerals have been found, and every year new ones are discovered. That's a lot of minerals! Don't worry! You don't need to know them all to be a rock hound. In fact, only a few dozen...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF