Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: garyisbackpacking on 22/09/2010 01:27:50

Title: Help Identifying Black Stone
Post by: garyisbackpacking on 22/09/2010 01:27:50

Found this stone many years ago during a backpacking trip in Siskiyou County in far northern California. Had it for many years before I became aware that it was translucent. Since then -- have been trying to ID it.  Is it obsidian?  Only thing - most obsidian I've seen has a more glassy, shiny look.  Any suggestions appreciated.
--Gary 

Title: Help Identifying Black Stone
Post by: traveler on 22/09/2010 03:06:32

I'd guess that it's an Apache tear. These are just tumbled obsidian.

Title: Help Identifying Black Stone
Post by: garyisbackpacking on 22/09/2010 04:23:46

Thanks. Much appreciate your response. 

It's puzzling because I found the stone in a remote wilderness setting miles from the nearest road and quite some distance off-trail.  It's difficult to tell from the photo but the stone looks quite worn and doesn't have a lot of reflective properties.  Some but not a lot.  And in diffused light, the black looks almost flat -- and can't detect any sign of the glassy aspect I've always associated with obsidian.  It doesn't look like it has been artificially tumbled but would like to know for sure -- is there any way to determine this?
-Gary

Title: Help Identifying Black Stone
Post by: traveler on 22/09/2010 14:29:10

Here is the WIKI definition of apache tears
Apache tears are rounded nodules of obsidian (volcanic black glass) with diameter from about 0.5 to 5 cm. An Apache tear looks opaque by reflected light, but translucent when held up to light[1][2]. Apache tears are usually black, but can range from black to red to brown. They are often found embedded in a greyish-white perlite matrix[1][2].

 
An Apache tearThe name "Apache tear" comes from a legend of the Apache tribe: about 75 Apaches and the US Cavalry fought on a mountain overlooking what is now Superior, Arizona in the 1870s. Facing defeat, the outnumbered Apache warriors rode their horses off the mountain to their deaths rather than be killed. The wives and families of the warriors cried when they heard of the tragedy; their tears turned into stone on hitting the ground.

Title: Help Identifying Black Stone
Post by: garyisbackpacking on 22/09/2010 17:05:41

Thanks, traveler.

Think it probably is an Apache Tear. Doesn't look like one that has been recently tumbled, though. Judging from various web photos - the tumbled ones -- though similar in shape (and translucence) -- are much more shiny, reflective, with a somewhat glassy sheen.  This one doesn't have that and looks old -- old and with what appears to be signs of natural weathering. That and given the remote location where found -- made me wonder.

Thanks, again.

-Gary

Title: Help Identifying Black Stone
Post by: JimBob on 23/09/2010 02:58:52

One does not need a tumbler to make an Apache Tear. The originals were not made in one. They formed in stream beds where the water running in the stream does all the rounding.

Title: Help Identifying Black Stone
Post by: garyisbackpacking on 23/09/2010 19:22:09

Thanks, JimBob.

Just got back from showing the stone to an elderly towns-person -- a very knowledgeable, long-time rock and mineral collector. He agreed with the comments on the forum  -- thought it obsidian and likely had been naturally stream polished. (Not mechanically tumbled.) But he also thought that it might have had a bit of hand polishing at some point.  He noted the signs of wearing evident at several places on the stone -- speculated that it could have occurred from being carried -- in a pocket, bag or pouch. (Obsidian is widely found in this area of far northern California.)  He suggested that I take the stone to the archaeology dept. at Shasta College -- let the folks there have a look at it.

Thanks again, traveler, JimBob, for taking the time to reply.

Much appreciated.

-Gary Robertson