Elias Ashmole discusses Belief in "Angellical Stones" which Can Result in Apparitions.

By the Magicall or Prospective Stone it is possible to discover any Person in what part of the World soever, although never so secretly concealed or hid; in Chambers, Closets, or Cavernes of the Earth: For there it makes a strict Inquisitoin. In a Word, it fairely presents to your view even the whole World; wherein to behold, heare, or see your Desire. Nay more, It enables Man to understand the Language of the Creatures, as the Chirping of Birds, Lowing of Beasts, &c. To Convey a Spirit into an Image, which by observing the Influence of Heavenly Bodies, shall become a true Oracle; And yes this as E.A. assures you, is not any ways Necromanticall, or Devilish; but easy, wonderous easy, Naturall and Honest.Lastly, as touching the Angelicall Stone, is to be so subtill, saith the aforesaid Author, that it can neither be seene, felt, or weighed; but Tasted only. The voyce of Man (which bears some proportion to these subtill properties,) comes short in comparison; Nay the Air it selfe is not so penetrable, and yet (Oh mysterious wonder!) A Stone, that will lodge in the Fire to Eternity without prejudiced. It hath a Divine Power, Celestiall, and Invisible, above the rest; and endowes the possessor with Divine Gifts. It affords the Apparition of Angells, and gives a power of conversing with them, by Dreames and Revelations: nor dare any Evill Spirit approach the Place where it lodgeth. Because it is a Quintessence wherein there is no corruptible Thing: and where the Elements are not corrupt, no Devill can stay or abide.See Full