ON THE second floor of Hoffman Lab, at the end of the hall, there is a set of unimposing double doors to which only five people in the world have the key. The only outside clue to what goes on behind those doors is a black rubber mat on the hall floor which reads MOON ROOM in large white letters. At first sight, the two laboratories behind the locked doors appear no different than any other geology laboratory. However, one of the labs contains a large floor safe to which only two of the original five scientists have the combination. This safe contains some of the rarest treasures at Harvard-rock and durt samples brought back from the moon by the crews of Apollo 11, 12, and 14.

The moon samples, except those from Apollo 14 which have only been available for a few weeks, have probably been scrutinized more closely than any other material in the history of man. Special, clean, sealed laboratories, some far cleaner and more sophisticated than those at Harvard, have been built all over the world for the sole purpose of studying a few pounds of lunar dust and rock.

Now Apollo 14 has brought back a new shipment of material from a different part of the moon-the highlands-and these samples are slowly being distributed to the various research groups.

Within the next few weeks Harvard will receive the rest of its allotment of Apollo 14 samples, and the same extensive analyses already carried out on the Apollo 11 and 12 samples will be done on the new material. Then, at the end of July, Apollo 15 will bring back still more samples which, after undergoing six weeks of preliminary examination, will also be distributed by the Lunar Receiving Laboratory in Houston, Texas. Although Harvard's allotment will be small, the techniques used for studying the samples require very little material and much time. Considering the relatively short time between reception of the Apollo 14 and 15 samples, Clifiord Frondel, professor of Mineralogy and head of the investigating team at Hoffman Lab, was led to remark, "We are going to have lunar rocks coming out of our ears."

Frondel was also a member of the Preliminary Examination Team (PET) for Apollo 11 and 12. The PET is made up of scientists who have a broad knowledge of geology and are familiar with the various techniques of mineral identification and characterization.

On July 28, 1969, Frondel opened the first box of lunar samples as the world waited, open-mouthed, for his verdict. The world was disappointed. Immediate sight identification was made impossible by the adherent lunar dust covering and hiding the rocks. Frondel later remarked that the rocks were so covered with dust that, "You couldn't tell if they were Swiss cheese or granite."

After the rocks and dust were separated, in addition to undergoing the preliminary mineralogical examination, they were put through an exhaustive series of tests to ensure that they carried no organisms which might be harmful to man. During this time the samples were in complete isolation. Although there have been numerous incidents of isolation chamber leakage, most have been minor. The one major leak occurred during the quarantine of the Apollo 12 samples and required Frondel to enter quarantine for two weeks himself. Failure to find the lunar samples biologically dangerous has led to the quarantine being abandoned.

Following the initial tests, most of the samples were put in storage at the Lunar Receiving Laboratory for future study. The remaining material has been distributed to some 175 research teams all over the world.

THERE ARE three such groups at Harvard. One group headed by Frondel and Cornelius Klein Jr., associate professor of Mincralogy, is concerned with the mineralogy of the lunar samples. Another group headed by Edward L. Fireman, lecturer on Astronomy, has determined the time some samples have been exposed to cosmic rays by studying the radioactivity in the samples. Then, the very important subject of the organic substances and their possible implications about life are studied by Elso S. Barghoorn, professor of Botany. Finally, special types of moon rock called anorthosites which give clues about the moon's formation are studied by Ursula B. Marvin and John A. Wood, both associates of the Harvard College Observatory.

Over 500 scientists have been studying the lunar samples and have collected a formidable amount of information in the short time since July 24, 1969, when the first samples were returned to earth. They have used a variety of some of the most sophisticated techniques known and have developed new techniques when necessary.

The results of this effort are increases in knowledge about the moon itself and its history, about the earth-moon system, about the sun and the galaxy, and about some of the fundamental mysteries of the universe.

As the Apollo astronauts looked around them, they saw a true desert-devoid of life, devoid of water, devoid of atmosphere (some five per cent of the atmosphere of the moon is man-made). The level volcanic seas or mares of the Apollo 11 and 12 landing sites cover much of the near side of the moon and provided the first lunar samples. Here the volcanic bedrock has been repeatedly hit by meteorites and broken up so that a layer of broken rock and dust from 6 to 20 feet deep lies on the surface. Some of these rocks have been lying on the surface directly exposed to space for several million years, while the top inch of soil has been relatively unmixed for the last several hundred million years.

Its incredible unchanging nature makes the lunar surface a permanent record of solar flares, solar wind and ordinary cosmic ray activity over thelast several hundred million years. Such a record is invaluable for tracing the history of the sun and nothing on earth comes close to duplicating it.

The history of the moon is revealed by the different types of rock found there. Most of the rocks brought back from the lunar seas by Apollo 11 and 12 are titanium-rich basalt and gabbro. They appear to be once-molten lava from inside the moon which broke through the crust made of lighter anorthosite and crystallized to form the seas about 3.5 billion years ago.

The crust itself forms the lunar highlands and was crystallized about 4.5 billion years ago-about the same time the earth was formed. Recent Apollo 14 samples from the highlands are anorthositic and support the hypothesis of an anorthosite crust.