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I have been looking at the historical use of obsidian in arrowheads and spear tips due to its nature of concave breaking patterns.  But I also know that the obsidian is right in the middle on the moh scale.  Wouldnt direct pressure from a strike likely break the obsidian, making it a one use wonder?

Perhaps flesh would not break it, but a miss into a hard surface would make it unlikely to be intact correct?

I see a good about of its use in fiction writing and it spurns the question of viability.

Hi Kyle,
Early hunters used many materials for their weapons and tools.  They used what worked best for specific applications.  
Obsidian does fracture easily but that's the major reason early hunters used it.  The conchoidal fracture pattern can create an amazingly sharp edge, if you know what you are doing.  It will break if you hit a stone or another hard surface, but then so would a stone point.  It does what it's supposed to; cut.  
It has it's drawbacks but it was the best they had.  Stone is durable but can't be made as sharp as obsidian.  It is lighter than stone and can be shaped more easily.  Also, they didn't have metals such as iron yet.  There is certainly evidence that they used native copper but, although it could be hardened some, it can't be made as sharp as obsidian.  It is also not as common as obsidian.  
Besides the fact that nothing could be made as sharp as obsidian, another virtue is that you can make an arrowhead or knife blade much more easily and quickly from obsidian.  Remember these people were craftsman.  A modern "knapper" can make an arrowhead in just a few minutes.  Early hunters did this all their lives so they could probably knock one out very quickly.  So when one breaks they would just make another.
Because of their relative fragility, obsidian tools were essentially disposable, but this was the best tool for the job, the raw material was common, and they could be easily replicated.

Hope this helps.


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C. Robert Reszka, Jr.


I can answer any general geology question (rocks, minerals, stratigraphy, geomorphology etc.). My expertise is in the geology of the Michigan Basin, PreCambrian, Paleozoic and Recent. I can answer questions concerning mining and petroleum exploration and production and the laws concerning those activities. I can also answer questions concerning stratigraphy of the Michigan Basin. I will also answer questions about mineral and rock collecting in the Basin. I won`t be able to answer many specific questions on hydrology, geophysics or geochemistry. I may be able to answer very general questions in those venues.


I have been working for the State of Michigan for 36 years as a Geologist and a Resource Analyst. I have experience with Subsurface Geology and Petroleum Geology, mining in Michigan, and Sand Dune Mining and Protection issues.

Michigan Basin Geological Society

Decade of North American Geology.
Bedrock Geology of Michigan

BS Wayne State University

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