What are three facts about obsidian?
Origin and properties It consists mainly of SiO2 (silicon dioxide), usually 70% or more. Obsidian does not last forever. It is metastable: it changes very slowly. Over time, the glass becomes fine-grained crystals.
What are 2 uses of obsidian?
Obsidian was used to make knives, arrowheads, spear points, scrapers, and many other weapons and tools. Once these discoveries were made, obsidian quickly became the raw material of preference for producing almost any sharp object.
How old is the obsidian rock?
20 million years old
Although most rocks that form in the Earth’s crust are very old, obsidian is rarely older than 20 million years old which is young for a rock. It goes through a process called devitrification whereby it turns from glass to a rock.
Can obsidian be purple?
Color is dark green to dark brown and black, also can show sheens of gold or green, yellow, blue and/or purple coloration. Sometimes with white inclusions (Snowflake Obsidian). Luster is vitreous. Transparency: Obsidian is translucent in any stone of appreciable size.
What is a fact about obsidian?
Interesting Obsidian Rock Facts: Obsidian is also known as “nature’s glass” because of its glassy appearance. When obsidian breaks, the fractures are very sharp which is why it was used as tools in the Stone Age. Seventy percent of obsidian rock is made of silica. Obsidian can only form near active volcanoes.
What are two facts about obsidian?
obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.
Is obsidian magnetic?
The magnetic properties of obsidian have been recognized by geologists for some time and the causes subject to investigation (e.g., Schlinger et al., 1986). Basic glasses are reported to be more magnetic than acid glasses (George, 1924:370).
What is an interesting fact about obsidian?
Is obsidian a glass?
Is obsidian a liquid?
It is chemically similar to granite and rhyolite, which also were originally molten. Because obsidian is not comprised of mineral crystals, technically obsidian is not a true “rock.” It is really a congealed liquid with minor amounts of microscopic mineral crystals and rock impurities.
What are two interesting facts about obsidian?
What is special about obsidian?
Obsidian is quite unique due to its smooth, uniform volcanic glass texture. Obsidian is usually considered an extrusive rock, because it usually solidifies above Earth’s surface where the edges of a lava flow come into contact with cool air or water.
What are the special features of obsidian?
Obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.
What is obsidian used for?
Obsidian can be used to make extremely sharp knives, and obsidian blades are a type of glass knife made using naturally occurring obsidian instead of manufactured glass. Obsidian is used by some surgeons for scalpel blades, although this is not approved by the US Food and Drug Administration (FDA) for use on humans.
What minerals are in Obsidian?
Obsidian is a black, extrusive igneous rock that is often called volcanic glass due to its absent crystals and glassy appearance. Major minerals include feldspar, quartz, and mica. Obsidian cools so quickly outside of the volcano that individual crystals do not have time to grow. An information card with details on…
What are the characteristics of obsidian?
obsidian (ŏbsĬd´ēən), a volcanic glass, homogeneous in texture and having a low water content, with a vitreous luster and a conchoidal fracture. The color is commonly black, but may be some shade of red or brown, and cut sections sometimes appear to be green.