Divination deals with discovering hidden or special knowledge by supernatural methods. Scrying is one of the many types of divination. Joseph Smith practiced scrying when he looked into a rock to find treasure and when he translated the Book of Mormon.
From Wikipedia (emphasis ours):
Scrying (also called seeing or peeping) is the practice of looking into a translucent ball or other material with the belief that things can be seen, such as spiritual visions, and less often for purposes of divination or fortune-telling. The most common media used are reflective, translucent, or luminescent substances such as crystals, stones, glass, mirrors, water, fire, or smoke. Scrying has been used in many cultures in the belief that it can divine the past, present, or future. The visions that come when one stares into the media are thought to come from one's subconscious and imagination, though in the past they were thought to come from gods, spirits, devils, the psychic mind, depending on the culture and practice.
Scrying is actively used by many cultures and belief systems and is not limited to one tradition or ideology. The Ganzfeld experiment involves sensory deprivation which might be seen as comparable with scrying. Like other aspects of divination and parapsychology, scrying is not supported by mainstream science as a method of predicting the future or otherwise seeing events that are not physically observable.
"Scrying," Wikipedia. Link is here.
In many early accounts from non-Mormon sources, they referred to Joseph Smith as "peepstone Joe" or said that he used "peep stones" to look for treasure or translate the Book of Mormon.
Joseph, and the prophets since, are called seers for their ability to "see" what others can't. However, the first time Joseph was called a seer was long before Mormonism began and he received his designation as prophet, seer and revelator. In the 1826 trial/examination in which Joseph was accused of using his stone, thereby being a "disorderly person," his father, Joseph Smith Sr., was sworn in as a witness (our emphasis):
He confirmed, at great length all that his son had said in his examination. He delineated his characteristics in his youthful days—his vision of the luminous stone in the glass—his visit to Lake Erie in search of the stone—and his wonderful triumphs as a seer.
Reported by William D. Purple in "Joseph Smith, The Originator of Mormonism," Chenango Union, Norwich, NY, May 2, 1877, Vol 30, No. 33. Found online Link is here.
The use here is in keeping with scryers being called seers, not a religious designation. Notice the inclusion of words "luminous" and "glass."
Scrying is practiced by many people today. Marianna Boncek describes how she scries and gives tips for others who are learning. ("Divination by Scrying: A Second Sight," The Llewellyn Journal. Online Link is here.) Donald Tyson's book Scrying for Beginners covers the basics. (Llewellyn Publications (1997). Amazon Link is here.)
Scientists reject divination in all of its forms, ascribing it to the realm of the occult and pseudoscience, along with astrology, fortune telling, numerology, witchcraft, mysticism, voodoo, etc.
If devout Latter-day Saints reject the modern use of scrying, they must explain why Joseph Smith was able to use that method for revelations and translating the Book of Mormon. They must also explain why people today claim, just as Joseph Smith did, that they receive information through scrying. If they accept that people are able to successfully scry today, but claim that the source from which the revealed information comes is suspect, they must explain why Joseph Smith's revelations were acceptable, but today's scryers' are not. Should members invest in mirrors, stones or crystal balls to receive revelation? If they did, would they be disciplined by the Church for their use? If a man were bring a crystal ball with him into the circle to bless his baby, and looked in it to give the blessing, what would the reaction be? If Joseph could harness mediums of divination for good, why can't each member today do the same?
Clay L. Chandler explores the relationship between Joseph Smith and scrying in a piece titled "Scrying for the Lord: Magic, Mysticism, and the Origins of the Book of Mormon." Dialogue, Vol. 36 No. 4. PDF file
"The Locations of Joseph Smith's Early Treasure Quests," by Dan Vogel covers not only the treasure seeking locations of Joseph Smith, but elements of magic and scrying in the early Life of Joseph Smith and others in the Palmyra area. Dialogue, Vol. 27. No. 3. PDF file
D. Michael Quinn's ground-breaking work on Joseph Smith and magic is Early Mormonism and the Magic World View. "This thoroughly researched examination into occult traditions surrounding Smith, his family, and other founding Mormons cannot be understated. Among the practices no longer a part of Mormonism are the use of divining rods for revelation, astrology to determine the best times to conceive children and plant crops, the study of skull contours to understand personality traits, magic formulae utilized to discover lost property, and the wearing of protective talismans. Ninety-four photographs and illustrations accompany the text." Signature Books; 2nd Edition edition (1998). Reviews, excerpts and a link to buy available from Signature Books website.
The Llewellyn website has a lot of information regarding scrying. Here are a few. "Divinatory Practices," The Llewellyn Encyclopedia. "There are hundreds, perhaps thousands, of different forms of divination and clairvoyant practice." "Crystal Ball Scrying" by Barbara Moore. "Scrying to See Spirit" by Anna. "Scrying: Catch a Glimpse of Your Future" by Jennifer Spees.