Fractured Jasper

Fractured Jasper Pebble, Puget Sound

Jasper is one of the most common, colorful rocks among the beach cobbles of Puget Sound. It is composed of micro-crystalline quartz (e.g. its crystal structure is too tiny for the eye) and therefore is very hard and takes a nice polish.  Often the samples I find are broken, fractured or badly-shapen.

This one, however, had both a nice shape, and a handsome fracture pattern similar to the "crackle" in pottery glazes. Despite its symmetrical shape, I did not cut it, but simply polished the stone as I found it, which rounds out sharp edges, but otherwise changes the rock very little. To be honest, I enjoy these "natural" shapes much more than cut cabochons so popular in the jewelry business.  It will never be a necklace, but I enjoy it all the same.

Rock Revealed

Unknown rock, polished

A month ago, I posted about a trip to the outer coast of the Olympic Peninsula, and about the variety of rocks I found among the beach cobbles - most specifically this one.  I noticed it as distinct from all the rest even in its rough, straight-off-the-beach state. (see July 28 photo) .

Now, a month later, it has gone through the polishing cycle, and its really unusual patterning has been revealed.  It is hard, and has taken a good polish, indicating something silica-rich (rather than a softer, sedimentary rock) but beyond that, I haven't got a clue. A strange jasper formed at the boundary of two rock types?  The multi-colored zigzag pattern which is its most striking feature, makes it look like it was liquid at one point.

Anyhow, whatever its name - it's a beauty. But like most of the others I find, from an unknown source.

app. 3" long

Mystery Solved... "Variolites"

Variolite cobble, Crescent Formation, Olympic Peninsula WA

For several years I have puzzled over the origin of this stone type, which is a remarkably common component of beach gravels around the Olympic Peninsula. (See my earlier post of July 19) It is so common, in fact, that it argues for a local source.  I haven't found that source yet - but I think I have discovered what it is.
The answer came from Scott Babcock, Professor of Geology at Western Washington State University, who has studied the Crescent Formation extensively.  He proposed that they were something called a "variolite" said to be a metamorphosed basalt (possibly pillow lava).  He sent me Googling for the quite-famous (though not to me) variolites of Durance, France.  Bingo.
A quick look at some photos of the Durance rocks was all I needed - these are clearly related.  (And there is a LOT of  basalt in the Crescent Formation here.)
As I said, the outcrop source for this rock is not known, at least that I've been able to discover, but maybe one of these days...

Variolite from Maguelon, France (www.variolite.fr)

Further note : I was also able to confirm the name, and provenance of this rock with Rowland Tabor, Geologist Emeritus at the US Geological Survey and author of the Guide to the Geology of Olympic National Park. He refers to it in his book (page 67-68) as "globular devitrification structures."  Wow, that's a mouthful.  However, he wasn't able to confirm a bedrock source. That, I guess, I am going to have to find for myself!

Big Stories...in Miniature

Mini-faulted Jasper

I have just finishing polishing some recent finds from beaches along the Puget Sound shoreline that I've gathered over the past few months.  Two of my favorites are here.  The first, above, is one I like because it shows big ideas -- in miniature.  The rock is only 1.5 inches tall, but clearly shows the offset layers caused by movement along a very small, but obvious, fault. This phenomenon is common enough in nature, in scales both micro and macro, but it is not often displayed with such precision in a rock you can hold in your hand.

Petrified Wood

This is also a handsome miniature, an inch-long pebble of petrified wood. Not wildly colorful, but displaying the layers of both bark and what I can only assume is some darker heartwood. I knew I had a beauty when I found this one, but had to wait a month for it to go through the tumbling stages.

Both rocks beg the same question I mused about in a previous post: where could they have come from?  Found on a Seattle beach, both could very likely have been scraped off an outcrop in the BC coast range, or somewhere on Vancouver Island, by the massive glaciers of the Pleistocene. They could have been worn down to pebble size by ten thousand years of surf and tide. I'll probably never know.

The truth is, I just get a kick out of imagining the journey these rocks have taken to my desktop. Go figure.

Inside the Rock

Ape Cave Lava Tube, Mt. St. Helens

No, I'm not really rockhounding here - I'm exploring this remarkable two-mile-long lava tube on the southern slope of Mt. St. Helens.  Lava tubes are rare here in the Northwest, where the Cascade volcanoes tend to blow up, rather than extrude a lot of liquid lava.  Still, this is one of the finest lava tubes in the US, a near-perfect tunnel that you could nearly drive a bus through.

Very cool.

Petite Poppies

Orbicular or "Poppy" Jasper, Olympic Peninsula, WA

I first stumbled onto this rock as an intriguing pebble on a beach along the shores of Puget Sound, covered with tiny red orbs against a dark matrix. Only later did I learn that they are referred to as Olympic "Poppy" Jasper, from Washington's Olympic Peninsula. Although some sources (like Jackson..see below) describe an outcrop of the stone just west of Lake Crescent, most people find this along the coastal beaches. These were all from a brief walk along Rialto Beach just north of the Quileute River near Forks, WA (Home of the "Twilight" stories)

Most are small and uncommon, but as you train your eyes for them along these cobble beaches, they start to jump out at you. I filled a bucket full of them, although many are badly cracked and pitted and will probably not take a good polish.  These were some of my favorites which have been tumbled for a month or so - yet still show some cracking and pitting - testimony to the brittle nature of the basalt they weathered out of.

Still, they are handsome little stones that I am happy to have found. Someday I may go look for the outcrop, but for now, these will do.

In the Trenches

I am fairly new to rockhounding, and rely on published guides to help steer me towards locations with interesting rocks.  I have several :

Gem Trails of Washington by Garret Romaine

Rockhound's Guide to Washington Vol. 1 & 2, by Bob & Kay Jackson  (ca. 1970)

Both cover a lot of the same ground, but help a beginner like myself get started.

The downside is that many of the areas described in both books have been pretty well picked over by generations of rockhounds before me.  What that means in practice became clear to me this week, when I went to explore Salmon Creek near Toledo, Washington.  Known in the past for its carnelian agate and jasper, Salmon Creek may still produce new material, especially after winter storms scour the watershed.

Carnelian/Agate, Red and Green Jasper, Salmon Creek

To me, however, Salmon Creek looked like a war zone. Pocked with craters and rock piles, this was as close to industrial rockhounding as I've ever seen, with the stream diverted, and every gravel bar turned upside down. Not only did this look like a waste of my time - and it was - it was disheartening to see the creek degraded this way. I know there are State rules for digging in and around streams, and although I don't know all those rules, I'm sure most of them were broken here, certainly in spirit. If there were once salmon fry in this stream, I doubt many of them survived this onslaught.

In the end, I bushwhacked up the river a mile or so, and found a spot where, although there were still pits and piles, there was not the devastated look of the lower, more accessible, parts of the river. I found a few nice pieces of agate and lots of lovely green and red jasper. I'm sure others have found better before me, but at what cost? I did no digging, or screening.

This experience made me resolve to search out other, less-publicized locations, and maybe find a few of my own. Either way, I will do everything I can to minimize my impact on the environment around me.  I have never been a fan of open-pit or strip mining: why should it be acceptable for rockhounds?