Black rocks

From Lostpedia

A pile of black lava rocks for Bernard's sign in "S.O.S."

Jack in front of a black rock at the line

In episode "S.O.S.", Bernard starts building an SOS sign from black rocks he found in a lava field 1/2 mile inlands of the beach. The Island seems to be volcanic, like almost all islands in the Pacific, so it is feasible that it is composed in great parts of that black volcanic rock.

Volcanic and igneous rocks can contain large amounts of metals like Iron and Manganese (which make them black) and can form anomalies in the earth's magnetic and gravitational field. Most tektites, formed during meteorite impacts and in intense pressure and heat are also black, and can be mistaken for rocks although are really very hard glass.

Lava-formed coastlines are also apparent in the rocky vistas seen in the following episodes:

"Homecoming": As Jack gets the guns from the hidden Halliburton case.
"Exodus, Part 1": As the party hikes toward the Black Rock with Arzt and Danielle Rousseau.
"Exodus, Part 2": As the party returns from the Black Rock.
"Abandoned": As the Tailies are walking along the coast to the other side of the Island.
"The Other 48 Days": As the Tailies continue their trek.
"Live Together, Die Alone": As Desmond follows Kelvin out the coast and confronts him as he discovers his sailboat Elizabeth.
"S.O.S.": As Jack and Kate attempt a prisoner exchange with the Others at the Line.
"Tricia Tanaka Is Dead": As Hurley and Charlie roll the DHARMA van down a steep hill, narrowly avoiding crashing into some black rocks.

Miscellaneous

The skeletons that Jack and Kate discovered in the caves harbored a small pouch that contained one white stone and one black stone.
Claire had a dream about a "black rock" that she put down in her diary which Charlie read about. It is unknown what type of object she was referring to (whether it was a ship or a stone).
"Black rock" is whispered in the jungle.
The same type of rock was used to send the pillar of smoke that signaled the coming of the Others.
Sawyer ducks behind a black rock when approaching the helicopter. ("There's No Place Like Home, Part 1")

Cultural references

Greek myth states that Prometheus was tied to a black rock, possibly a mountain, as a punishment from Zeus.
Black rock, on the beach of Rarotonga, west of Avarua, marks the spot where the missionary Papeiha is thought to have landed on shore. Papeiha was the first Christian missionary on the island. [1]
"The Black Rock" is a poem by John Gould Fletcher (1886–1950) and dedicated to Thomas Hardy. The subject of the poem is a black rock in the sea, and there are several themes including how men are frail, yet love has longevity just as a rock in the sea. [2]
Black rock is another name for a place in Clevedon, Bristol, UK for a cave system near the M5 Motorway (aka Fox's Cave), where tradition alleges polar bears once dwelled.
There was a book titled Black Rock: A Tale of the Selkirks by Ralph Connor. [3]
In Hawaiian mythology, the "Black Rock" is a promontory designated as one of three great 'Uhane Lele, a sacred point where souls of the dead leaped into their ancestral spirit land.
In Native American mythology, in the legend of the "Green Man", the "Black Rock" is eluded as a spirit the Green man killed an evil spirit who was the son of a woman whose soul was contained in a black stone. A Black Rock Spirit figures among the superhuman guards that defended an island of bad spirits located in the middle of the ocean.
Black Rock City, NV is where the "Burning Man" festival is held. It was purported that M. David Benson himself was handing out Apollo Bars featured in The Lost Experience game at the festival.
The novel Gravity's Rainbow by Thomas Pynchon contains a song called "The Aqyn's Song" with the following lyric: "It is north, for a six-day ride,/Through the steep and death-gray canyons,/Then across the stony desert/To the mountain whose peak is a white dzurt./And if you have passed without danger,/The place of the black rock will find you."

Trivia

Lost is filmed on location in Hawaii, the islands of which were created by volcanism. Hawaii sits on what geologists call a "hot spot", and its residents have many words to describe different types of lava flows. Lava coastlines are sometimes visible in Lost, e.g., the cove.