Orhan marble (Modern: Liabo marble) is a special kind of rock with powers of repelling dark souls, associated with the moon of the light gods for its heavenly quality. It is not actually a mineral originating on the Great Moon, but rather a rare form of limestone that would work as a magical talisman with sufficient purity. In its purest form it is bluish-white and would glow bright blue in the presence of evil creatures or servants of the Unlife. The repulsion effect as a doorway would be an attack that had to be resisted between levels 2 and 10, and it glows if they succeed by less than 50 (without cloaking spells). This is only defined in the archaic context of the Shadow World history. There is no modern lore or definition for "Liabo marble" as a material, even though some of its properties are given in room descriptions.
The term is still explicitly used in the game in rare instances, and might be implicitly present in other old areas. It could be an implicit aspect of the warding mechanism on the gate of the Order of Voln, which the guard is able to tell whose souls have not been cleansed of darkness, especially masters of the Council of Light. The obelisk room in the Graveyard in the past conspicuously did not have creatures enter it, but the color of the marble is not right and Orhan marble does not seem to exist in old enough documentation to be relevant. Its property of warding off undead level 3 or lower seems even later.
I.C.E. Age Example
Ronan's Shrine in the Upper Dragonsclaw outside Wehnimer's Landing explicitly mentions it as the material of a wall. The material is also inside the shrine as a doorway, but there is no warding effect.
[The Shore of Dreams] Fel and pine trees crowd close to the shore of an almost perfectly clear pool. A low wall crafted from bright blue Liabo marble surrounds the tiny pond, encircling it in a loving embrace. The gleaming surface of the water is disturbed only by concentric rings drifting away from the waterfall lazily spilling down from an outcropping of rocks overhead. Though the shadows are deep here, an occasional beam of light pierces the darkness, illuminating the vivid colors surrounding you. You also see a faint path. Obvious paths: none [Beyond the Shore of Dreams] Tears spring unbidden to your eyes as you bask in the serenity found here behind the waterfall. The music of water rushing over the stones surrounds you, easing away the cares of the world as you ponder the liquid wall enclosing this room on two sides. Light angles down from a break in the rocks on the northern wall, illuminating the fine spray of droplets floating through the air so that you are in the midst of a tiny, swirling rainbow of glorious color. You also see a graceful Liabo marble arch. Obvious exits: out
The Temple of Lorminstra in Solhaven has a dais of Liabo marble, which retains the concept that the material glows. This is a throw back reference to older game lore, as Solhaven was not released until late 1998. Though it might simply borrow the term from the Shore of Dreams. The temple borrows various details from the much older one in the Landing. The dais does not repel Council of Light masters.
[Chamber of Manifest Grace] Shimmering light from brass sconces mounted at intervals around the room bathe an ornately carved dais of Liabo marble in a warm glow. The walls are hung with purple cloth trimmed with gold emblems bearing the seal of Lorminstra. A sweet, pungent aroma pervades the room from a pair of golden braziers burning to either side of the altar. Obvious exits: south >look altar Engraved around the base of the altar are scenes of death and rebirth celebrating the benevolence of Lorminstra. The pure Liabo marble seems to emanate with a faint aura causing the engravings to shimmer as if they were alive. You barely make out a single sigil carved upon the face of the altar and inlaid in gold. There appears to be something written on it. >read altar In the Common language, it reads: HOPE
Behind the Scenes
Orhan marble is briefly discussed in the context of the Graveyard on the Research:The Graveyard page. The obelisk for the graves of Kestrel Etrevion's sons is oddly made of marble instead of granite, and the creature roaming mechanics were once such that the undead did not wander into the room without being repelled into it. This was made in very early 1990 and the earliest reference to Orhan marble is page 69 of the Master Atlas Addendum from spring 1990, so there is probably no implicit meaning along these lines. Ronan's shrine (Reann) is later I.C.E. Age and explicitly plays off the documentation.