Take a look at this page where it explains how to do a hardness test:
You may need to purchase a hardness testing kit online to do this, or bring it into a show where an expert can help you.
Also take a look if it is fluorescent. If you can get access to a shortwave UV light, if its hyalite opal it will exhibit a strong green fluorescence (though chalcedony may as well). Also see if you can find more on your property to determine if you live on the source. Usually where there is one there is more...