Selenite refers to two different things depending on the context: a translucent crystal prized in spiritual practices, and a chemical compound (sodium selenite) used in nutrition, agriculture, and medicine. Most people searching this term are curious about the crystal, but the chemical form plays a surprisingly important role in health and industry. Here’s what selenite is used for across all of these areas.
Selenite as a Mineral
Selenite is the crystalline, transparent form of gypsum, a common mineral made of calcium sulfate. It’s soft, ranking just 2 on the Mohs hardness scale, which means you can scratch it with a fingernail. The crystals are typically colorless or white with a glassy, sometimes silky luster. They can grow remarkably large: Mexico’s Cave of Crystals contains selenite beams over 30 feet long.
Because it’s so soft and water-soluble, selenite isn’t used in jewelry the way harder gemstones are. Its primary appeal is decorative and, for many people, spiritual.
Spiritual and Metaphysical Uses
Selenite is one of the most popular crystals in energy healing and meditation practices. Crystal practitioners use it for three main purposes: cleansing energy, charging other crystals, and deepening meditation. None of these uses are supported by scientific evidence, but they’re central to how most people encounter selenite.
In energy work, selenite is considered a purifying stone. Practitioners believe it can clear negative or stagnant energy from a person’s body and surrounding space. Wands made of selenite are commonly passed over or around the body during these sessions. Some practitioners also place selenite near doorways or windows with the idea that it keeps a room’s energy clear.
Selenite is also widely used to “charge” or “cleanse” other crystals. The practice typically involves placing smaller stones on or near a selenite slab or bowl, based on the belief that selenite can restore and amplify the energetic properties of other minerals. This is one of the reasons selenite charging plates have become a popular accessory in crystal collections.
For meditation, practitioners often hold a selenite wand or place one on the chest pointing toward the head. Some use a second crystal touching the top of the head. The goal is to reach a deeper meditative state and, according to crystal healing traditions, access spiritual guidance or visualize past experiences. Whether or not you subscribe to these beliefs, many people find that holding a smooth, cool crystal during meditation simply helps them focus and relax.
Sodium Selenite as a Selenium Source
Sodium selenite is a completely different substance from the crystal. It’s an inorganic chemical compound that provides selenium, an essential trace mineral your body needs in small amounts. Adults need about 55 micrograms of selenium per day, with the tolerable upper limit set at 400 micrograms. Going above that threshold risks toxicity.
Your body uses selenium to build a family of antioxidant enzymes called glutathione peroxidases. These enzymes neutralize reactive oxygen species, the unstable molecules that can damage cells. They convert harmful compounds like hydrogen peroxide into water and harmless alcohols. Selenium-dependent enzymes also play a role in thyroid function and male fertility, where they protect developing sperm cells from oxidative damage.
Sodium selenite is only about 50% absorbed by the body, making it less efficient than organic selenium forms like selenomethionine (found in foods like Brazil nuts, seafood, and grains). However, inorganic selenite is better at boosting the activity of those protective antioxidant enzymes, which is why it remains a common supplement form. Selenium supplementation in the form of sodium selenite was historically used to prevent Keshan disease, a type of heart muscle damage linked to severe selenium deficiency in parts of China, though it could not reverse damage already done.
Uses in Livestock and Agriculture
Sodium selenite is the most widely used selenium supplement in animal feed. Selenium deficiency in cattle, sheep, goats, horses, and swine causes a condition called white muscle disease, characterized by muscle weakness, heart failure, poor growth, and potentially death. The problem is common in regions where soil selenium levels are naturally low.
The FDA regulates selenium more tightly than any other trace mineral in livestock feed because of its narrow margin between a beneficial dose and a toxic one. Cattle feed can contain up to 0.3 parts per million of selenium, and salt-based mineral supplements are capped at 120 ppm with a daily maximum of 3 milligrams per animal. For sheep, the limits are lower: 90 ppm in supplements and no more than 0.7 milligrams per day. Exceeding these levels can cause selenium toxicity and death.
Industrial Applications
Sodium selenite is one of several selenium compounds used in glass manufacturing. When making clear glass, iron impurities create an unwanted green tint. Adding selenium at concentrations around 200 parts per million produces a pink color that masks the green, resulting in the colorless “flint” glass used in bottles and tableware. At higher concentrations (150 to 400 ppm), selenium compounds create the bronze-tinted glass you see in some beverage bottles and architectural applications.
Early Cancer Research
Sodium selenite has shown preliminary activity against cancer cells in laboratory and early clinical settings. In preclinical studies, selenite demonstrated the ability to sensitize tumors to radiation therapy. A Phase 1 trial tested oral selenite given two hours before radiation in 15 patients with metastatic cancer. Doses up to 33 milligrams were well tolerated, with only mild gastrointestinal side effects. Most patients saw disease stabilization within the treated areas, and seven of nine prostate cancer patients experienced a drop in PSA levels ranging from 11% to 78%, along with significant pain improvement.
These results are very early. Phase 1 trials are designed primarily to test safety and find appropriate dosing, not to prove a treatment works. The numbers involved are small, and selenite is not an established cancer therapy. But the findings were notable enough to warrant further investigation into whether selenium compounds could enhance the effectiveness of radiation treatment.