One of many ichors.

A substance produced by the Insectoids with healing properties. When produced, the Insectoids deposit small amounts into tiny holes drilled through the Hive.

Due to its rarity, many consider it to be of great value.

“It takes months for the drones to produce even a small amount, but it has unique properties. Some say that, in great quantities, it can even bring a member of the hive back from the dead.” - Khathandor - The Hive (GS-ADV3)

When lit by flame, blue ichor becomes a glittering inhalant, to which some individuals are allergic;

You rub a small amount of the blue ichor onto the rubble. Then you set it on fire with the flame from your torch. This does nothing to clear the debris, but a glittering blue smoke fills the mine. The Dwarves happily breathe it in. As you inhale, you are filled with a sudden burst of energy, as if you’d caught a second wind. - The Hive (GS-ADV3)

You smear a small amount of the blue ichor onto a large wooden crate and then light it on fire. It creates a cloud of glittering blue smoke. Eregrun begins sneezing violently. - The Hive (GS-ADV3)

The fragrance is known to have healing properties. It can also be applied directly to a wound. Ingesting it is another option for some.

You pour a bit of the blue ichor into it and raise it to Nayo’s nostrils. As she breathes in the fragrance, a few of the bruises along her neck and face disappear. - The Hive (GS-ADV3)

In great quantities, it can even bring the dead back to life.

Blue ichor is able to counteract the corrosive properties of other elements.

You notice there is quite a bit of dirt and rust on the head of your pickaxe. You hold the metal end beneath the water cascading down the falls. Then, you add a drop of the blue ichor. With some vigorous scrubbing, you’re able to remove the corrosion. - The Hive (GS-ADV3)

You discover that when combined with red ichor, the combination allows you to sneak into the Hive without being detected.

You later find the Immortal Knight Imbri submerged in blue ichor. You realize that they had not been trying to kill her. They were helping her recover from her many wounds.