Does Obsidian Get Destroyed by Lava? A Geologist’s Perspective
The short answer is no, obsidian does not get destroyed by lava. In fact, obsidian is volcanic glass formed from rapidly cooled lava. However, the interaction between obsidian and lava is more nuanced than a simple yes or no answer. Obsidian can melt back into lava under certain conditions, but it doesn’t simply disintegrate upon contact. Think of it more like ice returning to water when heated – a change of state, not annihilation.
Obsidian: A Child of Fire
Obsidian is essentially volcanic glass. It forms when felsic lava (rich in silica) cools so rapidly that crystals don’t have time to form. This rapid cooling can happen when lava erupts underwater or flows into cooler air. The resulting material is amorphous, meaning it lacks a crystalline structure, and it has a characteristically smooth, glassy texture. It’s also typically black, though the presence of certain minerals can cause variations in color, such as mahogany obsidian (reddish-brown) or snowflake obsidian (with white cristobalite inclusions).
Because obsidian is lava, it possesses a similar chemical composition to the lava it originates from. Therefore, when subjected to the intense heat of fresh lava flows, it won’t spontaneously combust or vanish. What happens instead depends on several factors, primarily the temperature of the lava, the composition of both the obsidian and the lava, and the surrounding environment.
The Dance of Melting and Assimilation
When obsidian encounters fresh lava, it can undergo melting. If the lava is significantly hotter than the obsidian’s melting point (which is roughly around 1300-1500 degrees Celsius, depending on the exact composition), the obsidian will begin to soften and eventually melt back into a molten state. This molten obsidian then mixes with the surrounding lava, potentially altering the lava’s composition slightly.
However, the melting process isn’t instantaneous. The rate at which obsidian melts depends on the temperature difference and the surface area exposed to the heat. Larger pieces of obsidian will take longer to melt than smaller fragments. Furthermore, the surrounding environment plays a crucial role. If the lava is flowing rapidly or is exposed to cooler air or water, the cooling effects can counteract the melting process, slowing it down or even preventing it altogether.
Another important factor is the composition of the lava itself. If the lava is significantly different in composition from the obsidian, the mixing of the two molten materials can lead to interesting chemical reactions and the formation of new minerals as the mixture cools. Geologists often study these interactions to understand the complex processes that occur within volcanic systems.
In essence, obsidian isn’t destroyed by lava; it’s re-integrated into the molten rock from which it came. It’s a process of transformation, not obliteration.
Frequently Asked Questions (FAQs) About Obsidian and Lava
Here are some common questions I get asked about obsidian and its relationship with lava.
1. What is the melting point of obsidian?
The melting point of obsidian is generally between 1300 and 1500 degrees Celsius (2372 and 2732 degrees Fahrenheit). However, the precise melting point varies slightly depending on the specific chemical composition of the obsidian.
2. Can you find obsidian inside lava flows?
Yes, it’s possible to find obsidian within lava flows, particularly in areas where the lava cooled rapidly. This is often observed at the edges of lava flows or where lava has interacted with water. These pockets of obsidian represent zones of quicker cooling compared to the rest of the flow.
3. Does the color of obsidian affect its melting point?
Not significantly. While the color of obsidian can vary depending on the presence of trace elements, these elements typically don’t have a substantial impact on the overall melting point. The primary factor determining the melting point is the silica content.
4. How does obsidian form in the first place?
Obsidian forms when felsic lava cools rapidly. This rapid cooling prevents the formation of crystals, resulting in the glassy texture characteristic of obsidian.
5. Is obsidian considered a mineral?
Technically, obsidian is not a mineral. Minerals are defined by their crystalline structure, and obsidian, being volcanic glass, is amorphous. It’s more accurately classified as a mineraloid.
6. What are the uses of obsidian?
Historically, obsidian was used to make sharp tools and weapons due to its conchoidal fracture (the way it breaks, leaving curved, shell-like surfaces). Today, it’s used in surgical scalpels, decorative objects, and jewelry.
7. Can obsidian be created artificially?
Yes, obsidian can be created artificially by rapidly cooling molten glass of the appropriate composition. This is sometimes done in laboratories for research purposes.
8. Is obsidian found only near volcanoes?
Yes, obsidian is almost exclusively found in areas with a history of volcanic activity. This is because it requires the rapid cooling of lava, a process most commonly associated with volcanic eruptions.
9. What are some other types of volcanic glass?
Besides obsidian, other types of volcanic glass include pumice, scoria, and tachylite. Pumice is frothy and lightweight due to the presence of gas bubbles, while scoria is darker and more vesicular than pumice. Tachylite is a basaltic glass that is darker in color and richer in iron and magnesium than obsidian.
10. How does obsidian compare to regular glass?
Obsidian and regular glass share the characteristic of being amorphous solids. However, obsidian is formed naturally from cooled lava, while regular glass is typically manufactured from silica sand. Obsidian also often contains trace elements that are not present in regular glass.
11. What happens if you throw obsidian into water?
If you throw obsidian into water, nothing dramatic will happen. It will simply sink because it’s denser than water. However, the rapid cooling of lava in water is a common way for obsidian to form in nature.
12. Does obsidian conduct electricity?
No, obsidian is a poor conductor of electricity. Like other types of glass, it’s considered an insulator.
13. Can obsidian be polished?
Yes, obsidian can be polished to a high luster due to its smooth, glassy texture. Polished obsidian is often used in jewelry and decorative items.
14. How can you identify obsidian?
Obsidian can be identified by its glassy appearance, conchoidal fracture, and typically dark color. A hardness test can also be helpful; obsidian typically has a hardness of 5.5 on the Mohs scale.
15. Where can I learn more about geology and volcanoes?
There are many resources available for learning more about geology and volcanoes. Universities often offer courses in geology and volcanology. You can also find a wealth of information online from reputable sources such as the United States Geological Survey (USGS) and academic institutions. Furthermore, organizations like the Games Learning Society at GamesLearningSociety.org explore innovative approaches to education, including the use of games to teach science concepts, although they might not directly focus on geology. The Games Learning Society fosters learning and collaboration through game-based strategies.
Conclusion: Obsidian’s Fiery Fate
Obsidian’s relationship with lava is one of origin and potential reunion. While it won’t be “destroyed” in the traditional sense, it can melt back into the molten rock from which it was born, depending on the surrounding conditions. This fascinating interplay highlights the dynamic processes at work within volcanic environments and provides valuable insights for geologists studying the Earth’s fiery heart.