Fire Opal

Crystals are classified according to the manner of their creation.


These crystals, which are also called Magmatic, were and are formed deep in the superheated magma beneath our feet. They are pushed up by pressures which are created by the interaction between convection currents, magnetic influences & tectonic plate shifts.  If the process is slow, (millions upon millions of years) or if they are forming on the inner surface of  a huge gas bubble, the crystals can grow to be very large.

Faster growth usually means smaller crystals. If the process is practically instantaneous, due to rapid cooling, glassy obsidian is formed.

Magma differs in various parts of the world, this is why certain crystals, though of the same species can be unique in their individual qualities, for example, when we compare Brazilian quartz to Madagascan quartz crystals, the difference is quite easy to detect.

Igneous crystals are subdivided into Vulcanites & Plutonites. Vulcanites form close to or at the surface, while Plutonites, named after the god of the underworld, form deep beneath the crust. Another name for Plutonite is Intrusive. Plutonites formed in gas bubbles are called Pneumatolytic. When formed by boiling water under pressure are called Hydrothermal.

These various minerals form in several ways depending upon their density and make up.  When magma rises into underground fissures and caves the local rock is melted.  As the rock dissolves it sheds its’ minerals and releases gas. This raises the pressure even higher, creating new crystals.  These are called Pneumatolytic crystals due to the presence of gas in their formation.

When water is present, under these critical temperatures and pressures, it deposits minerals as “Druse” onto the walls of the subterranean fissures and caves. These become “Gangue” rocks.

Different crystals evolve from magma at varying depths depending on heat, pressure, water, and local rock mineral content.

Examples: Vulcanites………Rhyolite, Fire Opal.

Plutonites……….Aventurine, Peridot, Epidot, Rose Quartz.

Pneumatolytic….Apatite, Topaz, Lepidolite, Tourmaline.

Hydrothermal……Amazonite, Aragonite, Fluorite, Kunzite, Moonstone.

Copyright © Crystal Gateways 2005 – 2012. Amanda and Francis Moloney.


Needless it should be to say, but said it must be: Nothing written on this website should be considered before professional medical advice in the case of any medical condition whatsoever.  And, only an idiot, or a complete curmudgeon would believe otherwise!


Please feel free to use excerpts and links from this original copyright material on the provision that you have natural good manners and say where you got it:

Francis Moloney@

© Crystal Gateways 2012

Author: amras888

Francis Moloney @Amras888 Composer, instrumentalist and Logic 8 software user. Bereavement Counselor retired. A Philosopher now disabled, bedbound but happy. Love my wife, son, and dog.

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