Heavy Metal Rock EarthCache

Earthcaches are all about obtaining new information and knowledge regarding the world we live in. What better place to start the ROCK bottom. This earthcache will teach you about the different types of rock that surround us 

What are Rocks?

Rock type is usually defined as a particular kind of rock having a specific set of characteristics. Rock types are specific assemblages of minerals (most rocks are composed of minerals). Unlike minerals, rocks are much more vaguely defined. For example even rocks within one rock type may have a highly variable composition.

Still, there is a fundamentally sound reason to talk about such a vague concept as a rock type because these assemblages occur again and again in many different locations. Every rock has characteristics that reflect its process of formation; these are used to determine whether the rock is igneous, sedimentary or metamorphic.

The rock appetence maybe influence from its environment (desert, savannah, rain forest) but it is still characterize as the same family. For example one desert may differ completely from another (one is sandy and another rocky) but they both share something that is common (low precipitation). Exactly the same is true with rock types — one granite may be white and another red but they both have a similar composition (major minerals are feldspar and quartz).

The three major rock classification:

Igneous

Rocks that have solidified from a molten state. The Earth is believed to have been entirely molten in its early stages of development. Hence, all other rock types are derivatives of igneous rocks. There are two types of Igneous rocks: 
Plutonic: Rock from magma rising up from deep under the earth's crust, and solidifies as it cools before it reaches the earth's surface like Granite. 
Volcanic: Rock that was originally lava, hot magma that reached the surface of the earth before it hardened like Basalt.

Sedimentary 

Rock formed by the accumulation of particles on or near the earth's surface, and compacted down, often under extreme pressure, creating rock layers. There are three main types of sedimentary rocks: mudstone, sandstone, limestone.

Metamorphic

Just like their name, they are transformed rocks or in other words rocks resulting from changes within pre-existing rocks, by extreme pressure, temperature, and chemical activity.

Metals in Rock

As stated before rocks are made of minerals (to read minerals you can visit GC5RYEH). One type of minerals are metals, typically metals compounds occur as inorganic solids with regular chemical compositions and crystal structures. Although most metal-bearing mineral compositions comprise several elements, there are a few exceptions such as gold, which is found in its elemental form as a mineral called native gold. Gold, silver, copper and the platinum are also the only metals that occur in nature in larger amounts. This is attribute to their ability to resist oxidation and weathering process (see GC61Z44) over geological time scales. Iron which is one of the most abounded chemical (over 1100 minerals) is easily oxidize. The different oxidation states of metals in rock can occur not only as color spots but also effect the complete color of the rock as can be seen in red colors of the sand-stone in Jordan and south Israel or the purple color of the rocks in North Wales.

How to sort the rocks?

Start by getting an idea of your basic rock class—igneous, sedimentary or metamorphic. Next observe the rock's texture—its grain size and overall pattern—conduct a basic hardness test, and identify the minerals that compose it as well as you can. Also consider visiting this link for more information

How to log this cache?

You will stand in front a wall that is made of a rock that is extracted from clay mud that has accumulated at the bottom of primeval oceans. During the formation of mountain ranges, the pressure exerted crushed this clay layer, compacting it and making the rock less porous with a stronger cohesion. Conditions favourable for the formation of this rock are found in several places in Canada including Quebec:

1. Identify the specific type of rock (Family and Name) and can you see evidence to how it was formed on the rock itself?

2. What is the metallic mineral that is in this rock. Based on its color/shape is it in native or oxide state (for example rusting, decomposint, have more then one color) ?

3. How many pieces of this rock/ tiles you are the wall made of?