The Three Phases of Rock Formation
The definition of rock is a naturally occurring aggregate formed of one or more minerals. There are three major classes of rocks: igneous, sedimentary and metamorphic, referring to how they have formed. Understanding how rocks form gives us insight into the constant geological process the earth is subject to, involving the formation of rocks, which then break down and are formed again into something new.
I was first introduced to the idea of using this information as part of a healing process when I read Michael Gienger’s Crystal Power Crystal Healing several years ago. In this chapter I am combining the geological information with the esoteric. Some of the detail of the sub-sub-sections comes from Gienger, as mineralogy books tend to refer only to subsections (such as vulcanites and plutonites), although I have heard reference to sub-sub-sections, such as gangue rocks, in documentaries.
When using minerals in healing, I have a sense of the process my client is going through, and how the development phase of the crystals I choose may be relating to that process. Gienger takes this a step further, and recommends travelling to a place where a particular phase of rocks has formed, such as the sedimentary area I live in, and stay for a period of four days, to strengthen and enhance that process.
Igneous rocks are formed volcanically. If the magma, from which the rocks are formed, extrudes onto the surface of the earth or the ocean floor, the rocks come under the subsection known as volcanic rocks, or vulcanites. If the magma solidifies beneath the earth’s surface, they are catagorised as plutonic rocks, or plutonites.
Magma is like the super-saturated sugar solution you get when making jam. The sugar dissolves easily in the liquid when it’s heated. Depending on the speed of cooling, the substances within, like the sugar, begin to separate out and crystallise.
Examples: Obsidian (volcanic glass – the quickest cooling, when the magma flow is on the ocean floor, and minerals do not have time to crystallise), rhyolites (leopardskin jasper, ocean jasper), basalt (lava rocks), pumice and tuff, the last two being very light and porous, as they are the result of pyroclastic explosion, and are frothed with gas bubbles. The most common volcanic rock is basalt.
The most common plutonic rock is granite, formed deep in the earth’s crust, which crystallises into feldspar, quartz and mica.
- Liquid Magmatic Formation – Minerals that form from liquid magma beneath the earth, at extremely high temperatures. Examples: aventurine, hyacinth zircon, peridot, rose quartz (the depth and heat is why rose quartz seldom forms defined crystals).
- Pneumatalic Formation – This occurs when gases penetrate nearby rock, dissolving some of it.
Examples: apatite, topaz and tourmaline
- Hydrothermic Formation – When water vapour becomes liquid under high pressure, further minerals are formed from substances dissolved in this water.
Examples: aragonite, fluorite, kunzite, and feldspars such as amazonite and moonstone
- Gangue Rocks – As liquid magma reaches higher levels in the earth’s mantle and begins to cool, gas bubbles contained within the magma leave chambers in the cooling rock, which may vary in size from tiny to enormous. Water finds its way into the chambers, precipitating minerals, which cool very slowly due to insulating qualities of the rock.
Examples are all familiar members of the quartz species: agate, amethyst, chalcedony, citrine, clear quartz, smoky quartz
Implications in Crystal Healing:
Igneous rocks begin with the magma, which is a soup of melted rock, containing all possibilities and potential in the formation of minerals. They demonstrate a crystallisation process based on cooling and solidification, and represent potential and predisposition. Igneous minerals symbolise an aspect of spiritual potential, and can support and encourage the development of that aspect.
Sedimentary rocks are formed at or near the earth’s surface through sedimentation, following the weathering and breaking down of already existing rocks through wind and water erosion. These weathered rocks may have started their journey on top of a mountain, and may ultimately be transported by water down to the seabed. Particles or grains can be cemented together through a process known as lithification (sandstone for example), or mineral constituents of broken down material is precipitated to form the soluble minerals such as halites (salt) and gypsum, some banded iron formations, such as hematite with red jasper, and limestone. Other common sedimentary rocks include flint and shale. Layering is always evident in large sedimentary formations, and is a good identification aid. Fossils only occur in sedimentary rocks.
Bear in mind that this is a representation. You will notice that many metal ores occur as sedimentary minerals, but it is also true that areas around volcanic activity are extremely rich in metal ore deposits. There are two subsections of sedimentary rocks:
Examples: anglesite, anhydrite (angelite), calcite, dolomite (also forms metamorphically), selenite, pyrite
- Secondary Sedimentation Zones: Mineral-forming elements are released from the water to form compounds which are deposited as new minerals
- Oxidation Zone – above the water table
Examples: azurite, malachite, chrysocolla, dioptase, turquoise and variscite
- Cementation Zone – next to the water table
Examples: copper, silver, copper chalcedony and covellite
Implications in Crystal Healing:
Sedimentary formation demonstrates the influences of environment, and represents the shaping of our personalities and belief systems due to experiences in our past, such as our upbringing or traumatic events. Sedimentary rocks and minerals can help us to recognise and become aware of this shaping, and gradually let go of old patterns.
I usually point out to students that I live in a limestone house on a hill where limestone has been quarried for hundreds of years. What does this say about what I might need to work on?
Just as the name implies, metamorphic rocks go through a process of turning from one thing into another. They are formed in lower part of earth’s crust under extreme heat and pressure. The metamorphic process includes the formation of mountains, and the metamorphosis and transformation of minerals into entirely new rocks. The dynamic pressure can actually fold sedimentary rocks back on themselves. There are some excellent examples around the Cornish and Welsh coasts. Common metamorphic rocks are marble, slate, schist, gneiss and quartzite. Some minerals, such as olivines, feldspar, mica and quartz, are stable at high temperatures, and do not metamorphose, but may be found contained within metamorphic rocks.
In addition to the formation of mountains, metamorphosis also occurs in the following situations:
- Large Scale Metamorphosis – compression due to heavy layering.
Examples: garnet, jadeite (jade), kyanite (formed in slate layers), nephrite (also considered to be jade), serpentine, tiger iron, zoisite
- Small Scale Metamorphosis – in the near vicinity of extreme heat (volcanic chimney)
Examples: the corundums – ruby and sapphire
- Metasomatism – where an exchange of elements takes place
Examples: charoite, rhodonite, gold and blue tiger’s eye (tiger’s eye is formed through the replacement of asbestos with an iron-rich solution of quartz).
Implications in Crystal Healing:
Metamorphism demonstrates the spiritual process of transformation, and represents the burning off of anything that is not necessary. Metamorphic rocks stimulate inner transformation and encourage critical self-reflection.