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Colors of Rocks/Minerals at Black Star Canyon

A cache by birdcachers05 Send Message to Owner Message this owner
Hidden : 10/1/2009
1 out of 5
1 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

The Irvine Ranch Conservancy was established in 2005. It is a non-profit, non-advocacy organization, created to help care for the 50,000 acres of permanently protected wildlands and parks on the historic Irvine Ranch. The organization works with its partners to enhance the public’s appreciation, understanding and connection to the land, while helping other land owners and managers with all aspects of stewardship. The Conservancy contributes its resources, expertise and energy to achieve the best possible balance of preservation and public participation.

Nearly 40,000 acres of the 50,000 acres indicated above of open space on the historic Irvine Ranch have been designated a Natural Landmark by both the State of California and the U.S. Department of Interior. This honor recognizes the exceptional value of these lands to California and the entire nation.

Beautiful geological formations - including "the Sinks", “Dripping Springs” and the rock formations located at Black Star Canyon - plus a rich diversity of flora and fauna make the The Irvine Ranch a favorite among hikers, mountain bikers and naturalists.

This cache is placed with the permission from and in cooperation with the Irvine Ranch Conservancy. Access is limited; reservations for docent-led outings are required due to the area's sensitive habitat. Pre-registration is required for all programs. No walk-up registration is allowed, no exceptions. Registration for weekday programs closes at 4 p.m. on the day prior to the event and registration for weekend programs closes at 4 p.m. on the Friday prior to the event. A calendar of scheduled hikes can be found at or
Additionally, they can be reached at (714) 508-4757 to coordinate small or large group hikes for these Earthcaches and other hikes within the Conservancy boundaries.

Santiago Canyon embodies the romance and lore of Orange County's colorful history: The canyon's past is punctuated by coal-mining operations, grizzly bear hunts, manhunts and homesteaders. The canyon was a major thoroughfare for early settlers who settled in its scenic side canyons-Baker, Black Star, Silverado and Modjeska. Traces of Orange County's earliest residents were discovered at Black Star Canyon. Arrowheads and rocks pockmarked with grinder holes (signs that the Indians ground acorns to produce an edible gruel) have been found on the plateau high above the canyon, where a large Indian village once existed. Black Star Canyon got its name in the 1870's, when Black Star Mining Company began mining for coal that recently had been discovered there. The mining operation was short-lived, though, because the quality of the coal was so poor.

This cache is designed for kids, but can be enjoyed by all cachers.

Color can be used to help determine specific minerals in a rock. While this has been determined to be one of the least effective methods in identifying rock/mineral content, it does provide a starting place when including or eliminating mineral content from rock formations. The below are some examples of mineral and rock colors and related minerals/rocks:

Light Grey or Tan--Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Sand and the sandstone it creates can be an color (the sandstone would be reflective of the color of the base sand in its formation. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Colors will usually be light grey or tan. Sandstone has been a main building material dating back into most of history.

Red - Iron Oxide: When air touches iron materials over a long period of time the process will “rust” (oxidize) the iron minerals in the sediment to give a reddish color to the rocks. Based upon the type of base rock, and the amount of iron materials in the formation, the color of red will vary from very dark as seen below, to lighter pinks. Iron Oxide has historically been used as the basis for several paint colors including Burnt Sienna, Burnt Umber, Chestnut, Sienna, Venetian Red and Mummy Brown.

Dark Grey - Siltstone: Silt is a size term used for material that is smaller than sand but larger than clay. Siltstone is defined as having twice as much silt as clay.

Blue - Azurite: Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits.

Yellow - Sulfur: Sulfur in its native form is a yellow crystal. Common uses are primarily found in fertilizers, matches, insecticides and fungicides.

Green - Epidote: The color is green, grey, brown or nearly black, but usually a characteristic shade of yellowish-green or pistachio-green.

Metallic Gold - Pyrite: Its metallic luster and pale-to-normal gold-yellow hue have earned it the nickname fool's gold, but ironically enough, small quantities of actual gold can sometimes be found in pyrite. This is primarily sold in retail shops as it appears to be gold, but also had been used in old-time radios.

Metallic Grey - Mica: Mica is a flaky grey mineral that provides for a metallic look when seen with several layers together. Mica is used in stoves and lanterns as it is somewhat clear, but is heat resistant. Mica can also be found in paint, wallpaper, roof paper, cosmetics and insulators, as well as other common applications.
In order to log this cache, from the coordinates, you will need to identify three rock/mineral types provided above. Please face west and look both at the formations at approximately 315 degrees and then at approximately 225 degrees.

1. At 315 degrees, you should see two different and distinct colors in the rock formations. Email me (logs that provide the answer will be deleted) both colors, and based upon the above what type of rock or mineral content you think both individually contain.
2. At 225 degrees, about 1/3 up from the bottom of the formation, there is a different color of rocks compared to the rock and/or mineral identified in #1 above. Email me (logs that provide the answer will be deleted) what color this formation is, and based upon the above what type of rock you think it is.
3. Based upon the colors discovered, email me (logs that provide the answer will be deleted) which mineral do you see the most of.
4. Also, post a picture with you, your group and your GPS from the coordinates with the formation in background.

References: (visit link)

Steven Dutch, University of Wisconsin-Green Bay http//
Wikipedia: (visit link)
Kidipede (visit link) (visit link) (visit link)

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Current Time:
Last Updated: on 1/8/2018 10:20:45 AM (UTC-08:00) Pacific Time (US & Canada) (6:20 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum

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