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Crystal Cave of Giants Naica, Mexico - Sept 3 - 6, 2009 Air Temperature of 50C(122F) + Relative Humidity of over 90% = Humidex Value of 105C (228F) !! This is one of the most extreme places on the planet. The Crystal Cave of Giants was accidentally discovered in 2000 by miners working in the silver and lead mine at Naica, Mexico. It lies almost 300 meters (900 feet) below the surface of the Earth and it contains the largest crystals known in the world, by far. The largest crystals are over 11 meters long (36 feet) and weigh 55...

Halemaumau emissions plume, half-size (click for full size): Wheeler Geologic Area, Colorado -- love the hoodoos. Apparently this place is so hard to reach that there was an attempt to make it a national monument, but that attempt collapsed because of lack of interest and potential visitorship, so it's a geological area in a national forest. Wheeler Geologic Area Crystal Cave of Giants, Mexico: Giant Crystal Cave's Mystery Solved (this article has a link to a different cave discovery, a very nice limestone cave in Sequoia National Park). It's pretty amazing that places like these are still being discovered in...

Rare green crystals found in 2,500-year-old tomb (Xinhua) Updated: 2007-07-04 16:43 JING'AN -- Chinese archaeologists exploring a 2,500-year-old tomb in east China's Jiangxi province that contained 47 coffins in a remarkable state of preservation were stunned to discover several pieces of green crystal lodged in the bones of the skeletons in the coffins. One of the diamond-shaped crystals was 8.5 centimeters long. The coffins also contained bronze, gold, silk, porcelain and jade items and even body tissue. Archaeologists said the crystals appeared to have "grown" in the bones. They pointed out that the coffins were made from halved nanmu, a...

How Vikings Might Have Navigated on Cloudy Days By Corey Binns Special to LiveScience posted: 02 March 2007 08:33 am ET Vikings navigated the oceans with sundials aboard their Norse ships. But on an overcast day, sundials would have been useless. Many researchers have suggested that the on foggy days, Vikings looked toward the sky through rock crystals called sunstones to give them direction. No one had tested the theory until recently. A team sailed the Arctic Ocean aboard the Swedish icebreaker Oden and found that sunstones could indeed light the way in foggy and cloudy conditions. Would have...

Thunder eggs are spherical objects which form in some types of silica-rich volcanic rocks (e.g. rhyolites). As the volcanic lava cooled, trapped steam and other gases formed an expanding bubble. Silica and feldspar minerals often crystallise around the bubble or grow crystal fibres which radiate outwards from the its centre. These mineral-filled bubbles with a radiating structure are called spherulites. Internal gas pressure forces the spherulite apart to form a central hollow, later filled with more minerals. Adjacent wedge-shaped segments of the cracked and expanding spherule move outwards and away from each other, helping form the typical star-shaped interior. Silica...

I've been meaning to do this for a long time. Below is a fine specimen of banded tourmaline. Tourmalines like this are generated in pegmatites; see diagram below the picture, with description and link to more information. (The diagram is not from the same place as the description.) The Pegmatite Zone, from whence cometh this text: "A pegmatite is a coarse grained igneous rock (formed deep within the earth) having a grain size of 3cm or more. Mostly pegmatites are granitic in origin, that is they are composed of granite and its constituents like quartz, feldspar and mica. In addition...

While public officials, schools, and the ACLU worked overtime this year to ban every vestige of Christmas from the public square, the recently invented holiday known as Kwanzaa is gaining in popularity among black Americans. These occurrences are not unrelated. In an earlier time, blacks held a strong faith in God. But over the past 40 years, the black community has largely let God slip away. Sure the community has maintained the outer trappings of religion, but the solid morality at its core is nearly gone. Enter a God-hating black racist named Ron Karenga. Born Ron Everett on a poultry farm...

Link post, to alert interested Free Republic readers the chance to access the thread in the "Chat" section, where any commentary should be posted: Geology Picture of the Week, October 17-23, 2004: Etna Otherworldly, plus Epidote

First of all, one might think I'm Etna-obsessed. Not true; I posted some images of the Piton de la Fournaise effusive eruption before this. But the Etna pictures continue to be interesting, so why not? This one, primarily due to the cold lava spires in the background, looked like a science-fiction movie set (shrunk for display, click to see the full-size image): And now for something completely different; here's an article I happened to read in the doctor's office. I couldn't find the image accompanying the article, so I found a different image of an epidote crystal. The article was...

Link post, providing a link to the thread in the FR "chat" section, where any discussion and comments should be posted: Geology Pictures of the Week(s), April 11-24, 2004: Microgeology

Worth repeating. Although I'm sure you're all too narrow-minded and angry to consider words like these. But... Please remove the word "Free" from your name. You poor folks don't have a clue. Have everyone read the Constitution again... carefully and, perhaps, sober this time. Sad and pathetic.. an wholly UN-American Signed David (Who loves truly American ideals)

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 December 30 A Sun Pillar Credit & Copyright: Dave Liquorice Explanation: Have you ever seen a sun pillar? When the air is cold and the Sun is rising or setting, falling ice crystals can reflect sunlight and create an unusual column of light. Ice sometimes forms flat, stop-sign shaped crystals as it falls from high-level clouds. Air resistance causes these crystals to lie nearly flat much of...