Dimensional Stone Cutting Saw, Index Granite Quarry, Washington State
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- čas přidán 8. 07. 2024
- This video features the historic building circular stone saw from the Index granite quarry, Index, Washington, USA (using 360 degree photography). The Index granite is an igneous rock. A sample of the Index granite is located at the base of the historic saw (both in front and in back of the saw), and also featured in the steps of the Washington State Capitol (later in the video). The Index Granite is the trade-name for a historic building stone--used mostly in the Seattle, Washington area. Building stone was produced from the quarry starting in 1894?- to the 1960s. The quarry is just west of Index (note that the heyday for building stone was until about 1930). This quarry mostly produced dimension stone, street curbing, tombstones, and cobblestones. Many buildings from the early 1900s, in downtown Seattle, feature this stone. Perhaps the best known building containing Index Granite is the foundation of the Legislative building, in the Washington State Capitol, in Olympia (it is featured in this video--however, most of the Legislative building is made of Wilkeson sandstone). The old Index granite quarry site now is a popular park for technical rock climbing. The historic circular saw from the quarry, has been relocated as a historical monument in the Index city park.
Note that the Index granite is technically a borderline granodiorite. But to keep things simplified (and to use its common architectural trade name), I will use the more common building stone term of granite.
Granite is a coarse-grain, intrusive, felsic rock that often contains the mineral quartz (which is colorless, translucent glassy to waxy). Note again that the Index granite is more of a intermediate rock--that contains very limited quartz minerals. Therefore, it is black and white in color and similar to diorite (and types of granite with a similar black and white color). As the name granodiorite implies, the rock has the mineralogical composition of between a granite and a diorite. The Index Granite is a part of the Oligocene Index Batholith (about 34 million years old). The exposed bedrock area covers 285 square km (or 110 square miles). [reference: pubs.usgs.gov/imap/i1963/skyp...].
Granite, diorite and granodiorite, are intrusive volcanic rocks (igneous rocks) that form by cooling very slowly deep underground (often in a magma chamber below a volcano). This long cooling time allows the minerals in the rock to grow to visible, coarse grain size.
The rounded shape xenoliths (roughly of potato-size and shape from this quarry), form darker, grayish spots within the Index Granite. The xenoliths are from what is known as "country rock". Country rock are rock fragments that become dislodged from the sides of a magma pipe and were incorporated within the rising magma (below a volcano). These xenolith rock fragments have a different composition than the magma associated with a volcano's magma chamber. Usually, xenoliths originate below a volcanic magma chamber, and have a darker color (more mafic composition than the associated rock that surrounds the xenolith).
The building stone steps of Index granite (shown in this video) contain several xenoliths (note that a concrete sidewalk is located at the bottom of the granite steps). Xenoliths made the Index Granite economically less desirable as a building stone. Consistent color throughout a building and monumental stone is preferred. The dark "spotted areas" in the granite are associated with the xenoliths. The darker xenoliths have a slightly different hardness than the surrounding black and white granite. Therefore, the xenoliths create more difficulty in stone fabrication--that requires precise cutting and carving across localities that contain xenoliths. However, the weather-resistant xenoliths can be beneficial in some circumstances. The local xenoliths create desirable hand holds and foot holds for rock climbers--that are exposed on the weathered rock cliffs near the old quarry.
Hello Rock People! This is Dave the Geology Dude! Identification notes for this rock are below in this text. Please be aware that the only way to really learn rock identification, is to have hands-on experience. Don't forget that Geology isn't rocket science--it's Rock Science! Please "like" and subscribe to this CZcams channel!
List of video chapters:
0:00 - 0:50: Description of the historic stone saw at Index, Washington
0:51- 1:18: Description of building stone products from the Index granite quarry, including the Washington State Capitol
1:18 - 2:01: State Capitol steps, with description of xenoliths (note that a concrete sidewalk is at the base of the granite steps)
Music (CZcams Audio Library): Epic Battle Speech (by Wayne Jones)
Copyright by David Knoblach, 2023. All rights reserved
Hello Rock People! This is Dave the Geology Dude! There is more to this video than just a spinning rock saw and a set of spinning stone stairs. There are detailed notes in the description area of this video. Please check out the many rock identification videos on my CZcams homepage too, or leave a comment here!
Absolutely Awesome !
Thx much Mike! Note that a much longer video is coming soon.
@@GeologyDude looking forward to it Dave!
A slurry of water and cracked steel shot? No abrasive grit? I am confused.
Good comment! The steel shot is hardened and it is the abrasive. The sign on the saw said this and I interviewed other stone cutters about this years ago from two other stone quarries-and also someone that worked at the Index. Quarry. I have even seen the shot that was used. Usually most quarries used much thinner blades of steel to move the shot. It is slow but cheap. Use of shot is a common process when making stone slabs. Here is an example of brucite marble with grooves from steel shot remaining in the cut stone: czcams.com/users/shortsvlhgt7Eds7o?si=Duqj3fUqMwtHmaXJ The grooves were later polished away after cutting.
@@GeologyDudeCannot wrap my head around it. How is the shot not flung all over, how did they feed it in, what’s the RPM? I’ve done almost every kind of lapidary, but industrial stonecutting is a whole ‘nother thing.
@@canadiangemstones7636 Here is a modern gang saw-cutting slabs in a stone block. czcams.com/video/ninPKwAIk5o/video.htmlsi=XaSHKIWj9nn-XJrF The modern saws may have diamond blades, but the old days the blades were just long pieces of steel, that eventually wore away too-and were replaced. The muddy water from cutting was just pumped back over the stone block. I’m not sure if new shot was added on top during the cutting process. It would take up to a day to cut through an entire stone block.
Stone cutting is rock surgery.
Ha ha, And this is a big tool todo the job!