OBSERVATIONS. I£ 
like the radiated zeolyte, but it is fo 
compadt and hard, that it gives fparks 
when ftruck with ft eel. In mineral 
acids it is not confiderably diflolved. 
Broken in pieces it ftiews conical figures, 
and preferves its fibrous appearance till 
it is powdered. The general colour is 
yellowifh, with concentric lines of lighter 
and darker colours, and fome quite black. 
I have not yet feen any one of this kind 
in its perfedt form, but always in broken 
pieces, either ofhollow fpheres or of folid 
ones, having a blackifti brown cruft 
upon their external fur face, which is 
fmooth and fpherical like fome haema¬ 
tites : pieces which are poflefled of this 
cruft are very rare. Sometimes there is a 
little white quartz joined to them. They 
are never found in veins or fifibres of 
any confiderable depth in the folid rock, 
but only walhed together in the valleys, 
which may be feen indeed by their round¬ 
ed furfaces. The ipecific gravity with 
refpedt to water at about 45 degrees of 
heat, 
