Is there anything you can tell me about this, who made it, or anything that might make it particularly special or rare?
First of all, what you have here is a Squash Blossom Necklace. To learn about its symbolism
Back in the 1970′s there was a “Native American jewelry boom” !!! You can search 1970 in the search tool on this blog and you will find several articles related to 1970s jewelry including this one
So because of that, there was a lot of Native American jewelry made at that time, some very nice and some kind of quick to feed the demand.
A good way to find out what your necklace is worth is to show it, in person to someone who deals specifically in vintage Native American jewelry. Another way is to use eBay to establish value. I outline a specific procedure you can follow to determine value in these articles:
As far as your necklace, it is fairly typical of the time. Although you only sent one photo of the front of the necklace, I can see that the stones are a very nice green turquoise, except for perhaps the one in the upper position which appears quite blue. That could be how it was originally made or it that stone could have been replaced at some point. Most of the squash blossom ends do show damage but they can be repaired by a Native American jeweler.
I couldn’t make out the inscribed hallmark well enough to verify and there have been a number of Navajo artists with the initials HL over the years.
Enjoy your treasure !