Magnesite

Magnesite (MgCO3) is a mineral which can interfere with sensor and transporter functions. (TNG: "Firstborn", "Inheritance"; DS9: "Nor the Battle to the Strong")

In the mid-22nd century, the Starfleet used magnesite in the production of their warp reactors. (ENT: "Bound")

In 2151, Malcolm Reed and Travis Mayweather broke a drilling rig's bit when the drill hit a layer of magnesite on Archer's Comet. (ENT: "Breaking the Ice")

In 2154, Harrad-Sar, an Orion trader, offered Captain Archer the coordinates of a planet rich in magnesite as part of a deal between Starfleet and the Orion Syndicate. (ENT: "Bound")

In the 24th century, magnesite fuel had replaced wood as the standard material for fires in the Federation. (VOY: "Tattoo")

In 2370, the Duras sisters and their associate Gorta illegally mined over 10,000 kilograms of magnesite from the Pakled-owned planet of Kalla III. The USS Enterprise-D tracked the magnesite to a Yridian buyer while the transaction was still taking place. Commander Riker purchased the Yridians' magnesite, and then beamed it into space and fired phasers on it to expose the Duras sisters' cloaked Bird-of-Prey. (TNG: "Firstborn")

The storage crate for the magnesite was a re-use of the Angosian police shuttle escape pod from TNG: "The Hunted", which was later seen again as Bok's Ferengi probe in TNG: "Bloodlines".

In 2371, an away team from USS Voyager was investigating magnesite deposits on Avery III when they were captured by Vidiians. (VOY: "Faces")

Magnesite is used in the hulls of Kazon fighters. (VOY: "Initiations")

A Federation hospital on Ajilon Prime was located near a large deposit of magnesite, preventing Julian Bashir and Jake Sisko from transporting to the surface in 2373. (DS9: "Nor the Battle to the Strong")

The surface of the planet Arakis Prime has a layer of magnesite dust. (VOY: "One Small Step")

Magnesite can provide partial protection against antimatter radiation. After an antimatter accident, Brin's people in the Delta Quadrant hid in magnesite-rich caves and lined makeshift environmental suits with magnesite to survive the radiation. However, they still suffered from widespread radiation poisoning. (VOY: "Friendship One")