Obsidian Tank – Parks, AZ Lapidary, Rockhounding Arizona

Filed under: regular postings — Gary October 14, 2006 @ 6:21 pm


Just north of Parks lies an area with a large quantity of Obsidian, perfect for various lapidary applications. The sizes of specimens vary from Nickel sized chips to softball sized rocks. Some material contains grey bands, which we guess to be solidified ash. Limestone is also prevalent here some containing fossils.


From Flagstaff head 17 miles West on Interstate 40. Get off on Exit 178 (Parks Rd.) Head north for a block then turn west on County Road 146 (old Route 66) Go .5 miles then turn right (north) on County Road 141 (Spring Valley Rd.) Go north for 7.2 miles (the pavement ends after 5.7 miles) then head east on Forest Road 100. This road will wind by a few houses, then at 1.7 miles you will arrive at Obsidian Tank. The tank (or pond) will be on your right, and Obsidian Road on the left. The area around Obsidian Road is a good place to park.

The Site

The tank just to the south contains a large amount of Obsidian and Limestone, however we found the gentle slope to the north to be a little more productive for the jet black Obsidian. This material is very well suited for faceting and polishing.

Other Points of Interest

We like to stop at the Parks Country Store (on the corner of Old Route 66 and Spring Valley Road) before heading out to the site. They have cold drinks and a deli here and anything else you might have forgotten back in Flag. Also, a few miles east of Obsidian Tank is the Kendrick Peak Trailhead, this hike takes you to the second highest mountain in northern Arizona. Even farther east is the Lava River Tube, a cave formed by molten lava tunneling though the earth. (Bring your jacket and extra flashlights, the temp inside is between 32 and 40 degrees and of course, very dark) Camping is also possible throughout this area in the Coconino National Forest.

Additional Information

The drive along these forest roads can be made in a passenger car in the drier months. We don’t recommend heading out during the snowier months without a four wheel drive. (If not at all!) A forest service map is also a good item to take along as most forest roads are clearly marked making navigation through the forest relatively simple.

About Obsidian


Obsidian is the result of volcanic lava coming in contact with water. Often the lava pours into a lake or ocean and is cooled quickly. This process produces a glassy texture in the resulting rock. Iron and magnesium give the obsidian a dark green to black color. Obsidian has been used by ancient people as a cutting tool, for weapons, and for ceremonial purposes and is sometimes found by archaeologists in excavations.

Obsidian has several varieties. Obsidian can contain small bubbles of air that are aligned along layers created as the molten rock was flowing just before being cooled. These bubbles can produce interesting effects such as a golden sheen, known as Sheen Obsidian or a rainbow sheen called Rainbow Obsidian. Inclusions of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern producing Snowflake Obsidian. Small nuggets of obsidian that have been naturally rounded and smoothed by wind and water are called Apache Tears.

Often confused with smoky quartz, obsidian has similar properties to quartz because of a similar chemistry. However, many properties dependant on a crystal structure are altered or absent in obsidian because it lacks any crystal structure of its own. The piezoelectric and optical properties in quartz are thus absent in obsidian. Smoky quartz usually has a splotchy or zoned distribution to its color while Obsidian’s color is more uniformly distributed.


  • 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.
  • Crystal System does not apply because obsidian is amorphous.
  • Habits include compact nodules or as massive layers between other volcanic rocks
  • Fracture is conchoidal.
  • Hardness is 5 – 5.5 (much softer than quartz).
  • Specific Gravity is approximately 2.6 (average)
  • Streak is white.
  • Other Characteristics: Generally lacks open voids or large bubbles like other volcanic rocks.
  • Notable Occurrences include Italy; Mexico; Scotland; Arizona, Colorado, Texas, Utah and Idaho, USA.
  • Best Field Indicators are color, fracture, flow bubbles, softness, association with other volcanic rocks and lack of crystal faces.

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