A close look at many items called "arrowheads" will reveal they are too heavy to be associated with arrows, but could have been used on spears of some sort.
The rock tools of Native Americans have a high percentage of quartz (silicon dioxide, Si O).
Photo is to show natural variation, you get one of these arrowheads Crudely knapped from black, volcanic obsidian by Apache Indians. Of the 3 arrowheads I purchased, I may be able to use one of them for wire wrapping, which is what I originally intended.
This product was terrible fair enough for the price I wasn't expecting anything beautiful but the arrow head i recieved didn't even come from a very good preform it was curved and twisted and only knapped on one side of the arrow head I would not recommend this I purchased two of these previously and was greatly pleased at what was sent me (see far left of photos).
This climate change around the end of the Pleistocene led to a gradual desiccation of the great bodies of water, and Lake Lahontan broke up into a series of smaller lakes and marshes by 9,000 years ago.